Lens driving apparatus, imaging apparatus, and lens barrel and camera main body used for this

ABSTRACT

A lens position calculator is provided that determines a phase of a driving signal as a reference position of an imaging lens when an output value of a position detection sensor reaches a threshold value. The lens position calculator determines a position obtained by performing addition or subtraction on the reference position read out from a reference position storage as a judgment position, detects an output value of the position detection sensor at a timing in synchronization with the driving signal that drives a driver and at the judgment position, and judges whether the output value of the position detection sensor at the judgment position reaches the threshold value or not, so as to determine the reference position again.

TECHNICAL FIELD

The present invention relates to an imaging apparatus such as a stillcamera or a video movie, a lens driving apparatus that controls aposition of a lens of such an apparatus and relates to a lens barrel anda camera main body used for an imaging apparatus.

BACKGROUND ART

Conventionally, a method for detecting the origin of a lens unit isproposed in which when the lens unit is driven by a motor, aphoto-interruption member attached to the lens unit and a photosensorare used so as to monitor an output level of the photosensor at the timewhen the photo-interruption member transverses the photosensor (PatentDocument 1, for example).

A conventional lens driving apparatus is described below, with referenceto FIG. 58. FIG. 58 includes a schematic diagram and a block diagram ofan exemplary conventional lens driving apparatus. In an imaging device75, an image of a subject captured through a fixed lens 72 fixed to abarrel 71, a zoom lens 73 and a focus lens 74 is converted into anelectric signal. Based on the electric signal output from the imagingdevice 74, a signal processing unit 82 generates image data and contrastinformation for performing focus adjustment.

When the power of a main unit is turned on, a system control unit 81outputs an instruction to a focus motor control unit 80 so as to drivethe focus lens 74 to the side of the imaging device 75. Based on theinformation concerning a moving direction and a moving step from thefocus motor control unit 80, a focus motor driving unit 83 outputs adriving signal to a motor 79 so that a desired rotation direction andsuch a rotation movement amount can be obtained. The focus motor controlunit 80 also receives a rotation position of a zoom ring 76 that isdetected by a zoom ring position detection unit 84.

When the focus lens 74 reaches the proximity of the position indicatedby the dotted line of FIG. 58, a photosensor 78 is interrupted by aphoto-interruption member 77, so that an output signal level of thephotosensor 78 changes. When this output signal level exceeds a certainthreshold level (or falls below a threshold value in some circuitconfigurations), a counter provided for the focus motor control unit 80beforehand is reset so as to detect an absolute position of the focuslens 74. Concurrently with this, positional information of the focuslens 74 for focus adjustment is output to the system control unit 81.

In this way, the absolute position of the focus lens 74 and a positionalrelationship with the zoom lens 73 are controlled, whereby variousapplications can be considered. For example, even in the case ofperforming a zooming operation, the position of the focus lens 74 can becontrolled while maintaining the focusing condition, a retracting speedin an auto-focus function can be increased and a distance from a subjectcan be estimated from the absolute position information of the focuslens 74.

Meanwhile, in the case where a focus lens in an interchangeable lenstype imaging device is driven by a motor, an example of a lens barrelequipped with a motor that shifts a focus lens, a driving circuit thatdrives the motor and a microcomputer that controls a position of themotor is known conventionally.

Such a conventional imaging apparatus is described below, with referenceto FIG. 59. FIG. 59 includes a schematic diagram and a block diagram ofan exemplary conventional imaging apparatus. FIG. 59 shows an example ofan interchangeable lens type imaging apparatus capable of detaching alens barrel 88 from a camera main body 89, where the detaching can beconducted at a junction part (not illustrated) of a signal line betweena motor control unit 86 and a system control unit 81.

An imaging device 75 converts an image of a subject captured through afixed lens group 72 and 85 fixed to the lens barrel 88 and a focus lens74 into an electric signal. Based on the electric signal output from theimaging device 75, a signal processing unit 82 generates image data andcontrast information for performing focus adjustment.

When the power of a camera main body 89 is turned on, the system controlunit 81 outputs an instruction to the motor control unit 86 so as todrive the focus lens 74 to the side of the imaging device 75. The motorcontrol unit 86 reads out information indicating a relationship betweena subject distance and a focus lens position that is stored in a storagedevice 85. Based on the information concerning a moving direction and amoving step from the motor control unit 86, a motor driving unit 87outputs a driving signal to a motor 79 so that a desired rotationdirection and such a rotation movement amount can be obtained.

When the focus lens 74 reaches the proximity of the position indicatedby the dotted line of FIG. 59, a photosensor 78 is interrupted by aphoto-interruption member 77, so that an output signal level of thephotosensor 78 changes. When this output signal level exceeds a certainthreshold level (or falls below a threshold value in some circuitconfigurations), a counter provided for the motor control unit 86beforehand is reset so as to detect an absolute position of the focuslens 74.

With the use of the thus detected absolute position of the focus lens74, a retracting speed in an auto-focus function can be increased, and adistance from a subject can be estimated from the absolute positioninformation of the focus lens 74. Further, by using information on focusdeviation that is output from the system control unit 81 and informationon the focus lens position read out from the storage device 85, themotor control unit 86 can control the focus lens position.

The technology described in the following Patent Document 2 also relatesto interchangeable lens type audiovisual equipment. A control unit 119provided in a lens unit 127 refers to not only lens cam data 120 storedbeforehand inside a lens microcomputer but also an AF evaluation signalsent from a main body microcomputer 114, whereby a scaling operation canbe conducted while keeping a position where an AF evaluation value isthe maximum.

Further, Patent Document 3 describes a mechanism for detecting theorigin of a lens unit. FIG. 60 is a schematic perspective view of a mainportion of another exemplary conventional imaging apparatus. In FIG. 60,numeral 91 denotes a reset switch as a reference position (resetposition) detector that is fixed to a stationary member (notillustrated).

The reset switch 91 has a U-shaped main body as illustrated, and anupper horizontal strip portion 91 a (hereinafter called “top plateportion”) and a lower horizontal strip portion 91 b (hereinafter called“bottom plate portion”) of the main body are arranged parallel to anoptical axis of an optical system described later. A detection targetplate protruding from a lens holder described later can enter in a spacebetween the top plate portion 91 a and the bottom plate portion 91 b.

A photo-transmission element is attached to a lower face of the topplate portion 91 a, and a photo-reception element is attached to anupper face of the bottom plate portion 91 b so as to be opposed to thephoto-transmission element. The photo-reception element and thephoto-transmission element make up a photo-interrupter, where thephoto-reception element is connected electrically with a controller 90on a electronic circuit board via an electric wiring W1.

Numeral 92 denotes a focus lens holder that holds a focus lens group. Afeed screw engaging strip (or female helicoid member) 92 b provided witha screw hole threadably engaged with a feed screw 98 is provided aroundthe holder 92. Further, a sleeve-shaped sliding unit 92 c axiallysidably fitted to a first guide bar 96 and a projection strip 92 d witha U-shaped groove axially slidably fitted to a second guide bar 97 areprovided. Moreover, a detection target plate 92 a capable of enteringinto the space between the top plate portion 91 a and the bottom plateportion 91 b of the reset switch 91 is provided.

The feed screw 98 extends parallel to the optical axis of the lens andis fixed to a shaft of a stepping motor 94 for driving the focus lens.The first guide bar 96 and the second guide bar 97 extend parallel tothe optical axis of the lens and are fixed to a stationary member (notillustrated).

Numeral 93 denotes a zoom lens holder that holds a zoom lens group, andis disposed coaxially with and at a predetermined interval from thefocusing lens holder 92. A feed screw engaging strip (or female helicoidmember) 93 b provided with a screw hole threadably engaged with a feedscrew 99 is provided around the zoom lens holder 93.

Further, sleeve-shaped sliding portion 93 c axially slidably fitted tothe first guide bar 96 and a projection strip with 93 d with a U-shapedgroove axially sidably fitted to the second guide bar 97 are provided.Moreover, a detection target plate 93 a capable of entering into thespace between the top plate portion 91 a and the bottom plate portion 91b of the reset switch 91 is provided. The feed screw 99 extends parallelto the optical axis of the lens and is fixed to a shaft of a steppingmotor 95 for driving the zoom lens.

The stepping motor 94 is connected to the controller 90 via a wiring W2and the stepping motor 95 is connected to the controller 90 via a wiringW3.

In the thus configured conventional imaging apparatus, when the power issupplied by a power supply switch (not illustrated), firstly thestepping motor 95 begins to rotate, so that the feed screw 99 rotates.Thereby, the zoom lens holder 93 is shifted toward the front end of thescrew 99 along the feed screw 99.

Then, when the detection target plate 93 a enters into the space betweenthe top plate portion 91 a and the bottom plate portion 91 b of thereset switch 91, light bundle from the photo-transmission element as aphoto-reflector is intercepted by the detection target plate 93 a, andin response to this, the controller 90 drives the stepping motor 95while counting the step number, so as to shift the zoom lens holder 93to the initial set position.

Next, the stepping motor 94 rotates so that the focus lens holder 92 isshifted toward the front end of the feed screw 98. When the detectiontarget plate 92 a enters into the space between the top plate portion 91a and the bottom plate portion 91 b of the reset switch 91, thusintercepting light from the photo-transmission element, the controller90 accordingly drives this stepping motor 94 while counting the stepnumber, so as to shift the zoom lens holder 92 to the initial setposition.

In this way, in this conventional apparatus, the detection of the resetpositions of the zoom lens and the focus lens, i.e., the detection ofthe origins can be accomplished with the detection target platesprovided for the respective lens holders and one reset switch common tothe two lenses.

Patent Document 4 discloses a focus adjustment apparatus for camera inwhich a lens group and a stop are driven by a pulse (stepping) motorthat is pulse-driven in a one to two phase excitation manner. The focusadjustment apparatus for camera described in Patent Document 4 has threepulse motors including a pulse motor M1 for stop, a motor M2 for focusadjustment and a zoom motor M3. The origins of the pulse motor M1 forstop and the motor M2 for focus adjustment are detected using aphotosensor that is provided separately from a lens group and wings forstop that are members to be driven. As for the zoom motor M3, theabsolute position of the lens group is detected by a volume (variableresistor), and therefore the origin therefor is not detected.

Patent Document 5 discloses a lens driving apparatus having a steppingmotor. In the lens driving apparatus described in Patent Document 5, theorigin is detected by shifting a lens as a member to be driven at alimiting position that is regulated mechanically and thenreverse-driving the lens from the limiting position by a predeterminedmoving amount. According to Patent Document 5, such control allows theorigin to be detected with high precision.

However, in the conventional lens driving apparatus like FIG. 58, thepositional relationship between the photo-interruption member attachedto the lens unit and the photosensor differs in absolute position foreach detection operation because of errors in looseness of the lens unitin the driving direction and variations in mechanism and electricalproperties due to temperature and humidity changes in the operationenvironment, thus making it difficult to obtain suitable performance forrealizing a high quality image, etc.

Meanwhile, there is proposed a method in which two photosensors havingdifferent variation sensitivities in output level with respect to theshift amount of a photo-interruption member when the photo-interruptionmember traverses the photosensors are used. An output of the photosensorhaving a larger variation sensitivity is set at a start signal and theorigin is detected from an output of the photosensor having a smallervariation sensitivity. This method is advantageous for enhancing thedetection accuracy of the absolute position, but is disadvantageous interms of compact size and cost.

Further, in the conventional imaging apparatus like FIG. 59, a largescale of microcomputer is required for controlling both of the lensbarrel side and the camera main body side. Therefore, in aninterchangeable lens type imaging apparatus, it is difficult to realizea compact lens barrel and a low cost. Further, there is a variation infocus position because of errors of variations in mechanism andelectrical properties due to a temperature and humidity change in theoperation environment of the lens barrel, thus making it difficult toobtain sufficient performance.

Further, according to the origin detection method in the conventionalimaging apparatus like FIG. 60, the movement of the photo-interruptionmembers is detected with a common photosensor so as to detect theorigins. However, the photosensor is disposed between both lens unitsand that is located around the units. Therefore, the outer dimensions ofthe lens units increase, thus increasing the lens barrel in size.

Moreover, when storing the lens units, the lens units have to be closerto each other. However, in order to avoid the contact between therespective photo-interruption members at this time, the outer dimensionsof the photosensor should be increased. This becomes a factor oflimiting downsizing in the optical axis direction and its orthogonaldirection, which means an obstacle to downsizing of the lens barrel.

Further, in the origin detection method shown in FIG. 60, the followingproblems occur in the case of abnormal completion. The abnormalcompletion refers to the completion caused by a decrease in voltagebecause the battery for supplying to the imaging device becomesexhausted or careless detachment of a connection terminal to an externalpower supply during an operation using the external power supply, forexample. In this case, when the power of the imaging device is turned onnext, a process for detecting the origin of the zoom lens unit will benormally performed. In this case, if the light of the photosensor isinterrupted by the photo-interruption member of the focus lens unitbecause of a decrease in voltage, the process for detecting the origincannot be performed normally and a malfunction will occur. In this way,the conventional example having a photosensor used common to the zoomlens unit and the focus lens unit has several problems.

Further, the focus adjustment apparatus described in Patent Document 4requires the configuration such as a photosensor separately provided todetect the origin of the stepping motor, thus having a problem of beingincapable of achieving the downsizing of the imaging apparatus.

Further, the lens driving apparatus described in Patent Document 5detects the origin by shifting a member to be driven to the limitingposition that is regulated mechanically. Therefore, there is a problemthat an error occurs when the shifting amount from the origin isspecified from the pulse number applied to the stepping motor. Thisresults from, when the member to be driven is allowed to contact withthe limiting position regulated mechanically, the member to be drivenwill receive a magnetic force applied to a rotor magnet in a differentdirection depending on the exciting position corresponding to thelimiting position, and therefore the member to be driven is driven intwo ways depending on the timing when the origin is set, i.e., in thedirection toward the limiting position and in the direction away fromthe limiting position.

-   Patent document 1: JP H06(1994)-174999 A-   Patent document 2: JP H09(1997)-23366 A-   Patent document 3: JP H04(1992)-184309 A-   Patent document 4: JP H10(1998)-224680 A-   Patent document 5: JP H08(1996)-76005 A

DISCLOSURE OF INVENTION

The present invention is for solving the above-stated conventionalproblems, and it is an object of the present invention to provide a lensdriving apparatus that prevents the generation of a detection error ofthe origin without impairing the compact size, to realize a compact lensbarrel at a low cost in an imaging apparatus, and further to provide animaging apparatus and a lens driving apparatus capable of smooth origindetection and precise alignment control.

In order to fulfill the above-stated object, a first lens drivingapparatus of the present invention includes: an imaging lens including afocus adjustment lens that forms an image of a subject; an imagingdevice that images light of the subject by way of the imaging lens; alens position controller including a driver that shifts the imaging lensin a direction of an optical axis with respect to a lens barrel, thelens position controller outputting a periodic driving signal andcontrolling a position of the imaging lens using the driver; a positiondetection sensor whose output value varies with a position of theimaging lens; a lens position calculator that determines a phase of thedriving signal as a reference position of the imaging lens when theoutput value of the position detection sensor reaches a threshold value;and a reference position storage that stores the reference position. Thelens position calculator determines a position obtained by performingaddition or subtraction on the reference position read out from thereference position storage as a judgment position, detects an outputvalue of the position detection sensor at a timing in synchronizationwith the driving signal that drives the driver and at the judgmentposition, and judges whether the output value of the position detectionsensor at the judgment position reaches the threshold value or not, soas to determine the reference position again.

In order to fulfill the above-stated object, a second lens drivingapparatus of the present invention includes: an imaging lens including afocus adjustment lens that forms an image of a subject; an imagingdevice that images light of the subject by way of the imaging lens; alens position controller including a driver that shifts the imaging lensin a direction of an optical axis with respect to a lens barrel, thelens position controller outputting a periodic driving signal andcontrolling a position of the imaging lens using the driver; a positiondetection sensor whose output value varies with a position of theimaging lens; a lens position calculator that determines a phase of thedriving signal as a reference position of the imaging lens when theoutput value of the position detection sensor reaches a first thresholdvalue; and a reference position storage that stores the referenceposition. The lens position calculator designates as a judgment positiona position having a same phase as a phase of the reference position readout from the reference position storage, detects an output value of theposition detection sensor at a timing in synchronization with thedriving signal that drives the driver and at the judgment position, andjudges whether the output value of the position detection sensor at thejudgment position reaches a second threshold value different from thefirst threshold value or not, so as to determine the reference positionagain.

A first imaging apparatus of the present invention is such that a lensbarrel and a camera main body are detachable. The lens barrel includes:an imaging lens group that includes a focus lens and forms an image of asubject; a motor driver that includes a motor that shifts the focus lensin a direction of an optical axis; a storage in which an informationtable containing control information of the focus lens is stored; and afirst data transmitter/receptor that transmits information output fromthe storage to the camera main body. The camera main body includes: animaging device that images light of the subject by way of the imaginglens group; a second data transmitter/receptor that receives informationtransmitted from the first data transmitter/receptor; and a motorcontroller that controls the motor in accordance with receivedinformation output from the second data transmitter/receptor. The focuslens is controlled in accordance with information that the motorcontroller transmits to the first data transmitter/receptor via thesecond data transmitter/receptor.

A lens barrel of the present invention includes: an imaging lens groupthat includes a focus lens and forms an image of a subject; a motordriver that includes a motor that shifts the focus lens in a directionof an optical axis; a storage in which an information table containingcontrol information of the focus lens is stored; and a first datatransmitter/receptor that transmits information output from the storageto a camera main body. The lens barrel is used for the camera bodyincluding a motor controller that outputs information for controllingthe focus lens via a second data transmitter/receptor, and the focuslens is controlled in accordance with information that the motorcontroller transmits to the first data transmitter/receptor via thesecond data transmitter/receptor.

In a camera main body of the present invention that is used for a lensbarrel, the lens barrel includes: an imaging lens group that includes afocus lens and forms an image of a subject; a motor driver that includesa motor that shifts the focus lens in a direction of an optical axis; astorage in which an information table containing control information ofthe focus lens is stored; and a first data transmitter/receptor thattransmits information output from the storage to the camera main body.The camera main body includes: an imaging device that images light ofthe subject by way of the imaging lens group; a second datatransmitter/receptor that receives information transmitted from thefirst data transmitter/receptor; and a motor controller that controlsthe motor in accordance with received information output from the seconddata transmitter/receptor. The motor controller transmits informationfor controlling the focus lens to the first data transmitter/receptorvia the second data transmitter/receptor.

A second imaging apparatus of the present invention includes: a lensbarrel provided with a first lens unit and a second lens unit, each ofwhich is movable in a direction of an optical axis; a first driver thatshifts the first lens unit in the direction of the optical axis; asecond driver that shifts the second lens unit in the direction of theoptical axis; a controller that outputs a control signal to each of thefirst driver and the second driver; and a position detector that detectsa position of the second lens unit and also detects a position of thefirst lens unit by movement resulting from contact of the first lensunit with the second lens unit.

A third imaging apparatus of the present invention includes: a powersupply; a lens barrel provided with a first lens unit and a second lensunit, each of which is movable in a direction of an optical axis; afirst driver that shifts the first lens unit in the direction of theoptical axis; a second driver that shifts the second lens unit in thedirection of the optical axis; a controller, when electric power issupplied from the power supply or when the power supply is shut off,making the first driver shift the first lens unit so as to performpredetermined process operations for supplying the electric power orshutting off the power supply; and a storage that stores informationdifferent between a normal completion state and an abnormal completionstate, in which in the normal completion state the first lens unit andthe second lens unit are shifted to storage positions in accordance witha predetermined process operation when the power supply is shut off froma state of the supplying the electric power, and in the abnormalcompletion state the apparatus to which electric power is being suppliedis completed in a state different from the normal completion state. Whenelectric power is supplied after the abnormal completion state, thefirst lens unit and the second lens unit are returned to the normalcompletion state in accordance with the information stored in thestorage.

A driving apparatus of the present invention that drives a body to bedriven includes: a restriction end that restricts movement of the bodyto be driven; a stepping motor that drives the body to be driven byrotation of a rotor resulting from a change in exciting position inaccordance with a pattern of an exciting current; a driver that suppliesthe exciting current to the stepping motor; an origin storage unit thatstores an exciting position corresponding to an origin of the body to bedriven beforehand; a counting unit that counts the exciting positionvarying with the pattern of the exciting current supplied by the driverand an absolute position of the body to be driven corresponding to theexciting position; and a calculation unit that resets the origin. At theexciting position stored in the origin storage unit, the rotor receivesa magnetic force in such a manner that the body to be driven isseparated from the restriction end after the exciting position isadvanced so that the body to be driven is closer to the restriction endand when the exciting position is advanced further from a state wheremovement of the body to be driven is restricted by the restriction end.

A third lens driving apparatus of the present invention includes theabove-stated driving apparatus. The body to be driven is a lenssupporting frame that supports a lens element.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 includes a schematic diagram and a block diagram of a lensdriving apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a detailed block diagram of a focus motor control unitaccording to Embodiment 1 of the present invention.

FIG. 3 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 1 of the presentinvention.

FIG. 4 is a flowchart of the origin detection operation during theprocess adjustment according to Embodiment 1 of the present invention.

FIG. 5 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 1 of the present invention.

FIG. 6 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 1 of the present invention.

FIG. 7 is a graph showing the relationship between the zoom position andthe focus position according to Embodiment 1 of the present invention.

FIG. 8 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 2 of the present invention.

FIG. 9 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 2 of the present invention.

FIG. 10 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 3 of the presentinvention.

FIG. 11 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 3 of the present invention.

FIG. 12 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 4 of the present invention.

FIG. 13 is a flowchart of a power-off process according to Embodiment 4of the present invention.

FIG. 14 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 5 of the presentinvention.

FIG. 15 is a flowchart of the origin detection operation during theprocess adjustment according to Embodiment 5 of the present invention.

FIG. 16 is a block diagram of a lens driving apparatus according toEmbodiment 6 of the present invention.

FIG. 17 is a drawing for explaining an operation of an angle detectionsensor according to Embodiment 6 of the present invention.

FIG. 18 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 6 of the present invention.

FIG. 19 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 6 of the present invention.

FIG. 20 is a graph showing the relationship between the zoom positionand the focus position according to Embodiment 6 of the presentinvention.

FIG. 21 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 7 of the presentinvention.

FIG. 22 is a flowchart of the origin detection operation during theprocess adjustment according to Embodiment 7 of the present invention.

FIG. 23 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 7 of the present invention.

FIG. 24 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 7 of the present invention.

FIG. 25 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 8 of the present invention.

FIG. 26 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 8 of the present invention.

FIG. 27 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 9 of the present invention.

FIG. 28 is a flowchart of a power-off process according to Embodiment 9of the present invention.

FIG. 29 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 10 of the presentinvention.

FIG. 30 is a flowchart of the origin detection operation during theprocess adjustment according to Embodiment 10 of the present invention.

FIG. 31 is a drawing for explaining an origin detection operation duringthe normal operation according to Embodiment 11 of the presentinvention.

FIG. 32 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 11 of the present invention.

FIG. 33 includes a schematic diagram and a block diagram of an imagingapparatus according to Embodiment 12 of the present invention.

FIG. 34 is a block diagram of a motor control unit according toEmbodiment 12 of the present invention.

FIG. 35 is a drawing for explaining the operation of a datatransmission/reception unit according to Embodiment 12 of the presentinvention.

FIG. 36 is a flowchart of a lens initialization operation according toEmbodiment 12 of the present invention.

FIG. 37 is a drawing for explaining an origin detection operation duringthe process adjustment according to Embodiment 12 of the presentinvention.

FIG. 38 is a flowchart of the origin detection operation during theprocess adjustment according to Embodiment 12 of the present invention.

FIG. 39 is a drawing showing the relationship between temperatures andthe focus position correction amount according to Embodiment 12 of thepresent invention.

FIG. 40 is a schematic block diagram of an imaging apparatus accordingto Embodiment 13 of the present invention.

FIG. 41 is a drawing for explaining the mode transition of lens unitsaccording to Embodiment 13 of the present invention.

FIG. 42 is an operation flowchart of a power supply process according toEmbodiment 13 of the present invention.

FIG. 43 is an operation flowchart of a power supply process duringnormal state according to Embodiment 13 of the present invention.

FIG. 44 is an operation flowchart of a power supply process duringabnormal state according to Embodiment 13 of the present invention.

FIG. 45 is an operation flowchart of a power shut-off process accordingto Embodiment 13 of the present invention.

FIG. 46 is a drawing for explaining the operation of an origin detectionof a lens unit according to Embodiment 13 of the present invention.

FIG. 47 includes a schematic diagram and a block diagram of an imagingapparatus according to Embodiment 14 of the present invention.

FIG. 48 is a detailed block diagram of a control circuit in the imagingapparatus according to Embodiment 14 of the present invention.

FIG. 49 is a block diagram of a motor unit and a focus driver of theimaging apparatus according to Embodiment 14 of the present invention.

FIG. 50 is a timing chart showing a current pattern of the excitingcurrents applied to an A-phase coil and a B-phase coil of the motor unitof the imaging apparatus according to Embodiment 14 of the presentinvention.

FIG. 51 is a schematic diagram showing the relationship between theexciting positions of the motor unit and the driving positions atpositions far away from the restriction end in the imaging apparatusaccording to Embodiment 14 of the present invention.

FIG. 52 is a schematic diagram showing the relationship between theexciting positions of the motor unit and the driving positions atpositions closer to the restriction end in the imaging apparatusaccording to Embodiment 14 of the present invention.

FIG. 53 schematically shows the relationship between the directions offorces that a rotor magnet of the imaging apparatus according toEmbodiment 14 receives and the exciting position numbers.

FIG. 54 is a drawing for explaining the movement of a rotor of theimaging apparatus according to Embodiment 14 of the present invention.

FIG. 55 is an operation flowchart of an origin reset process of theimaging apparatus according to Embodiment 14 of the present invention.

FIG. 56 includes a block diagram of a motor unit and an iris driver ofan imaging apparatus according to Embodiment 15 of the present inventionand a schematic diagram of a stop.

FIG. 57 schematically shows the stop in the imaging apparatus accordingto Embodiment 15 of the present invention closer to the restriction end.

FIG. 58 includes a schematic diagram and a block diagram of an exemplaryconventional lens driving apparatus.

FIG. 59 includes a schematic diagram and a block diagram of an exemplaryconventional imaging apparatus.

FIG. 60 is a schematic perspective view of a main portion of anotherexemplary conventional imaging apparatus.

DESCRIPTION OF THE INVENTION

According to the first lens driving apparatus of the present invention,a reference position determined during the process adjustment is notdetected directly during the normal operation. Instead, at a judgmentposition different from the reference position, a reference position isdetected by judgment. Therefore, the generation of detection errors inorigin, resulting from a variation in mechanism and electricalproperties of a lens unit, can be prevented.

In the first lens driving apparatus of the present invention,preferably, the driving signal that drives the driver for determiningthe reference position is a substantially sine wave signal. With thisconfiguration, the reference position accuracy can be improvedsignificantly.

In the first lens driving apparatus of the present invention,preferably, assuming that a time of one cycle of the driving signal thatdrives the driver for determining the reference position is T, a drivingsignal that drives the driver for determining the reference positionagain is a M/N periodic driving signal whose one cycle is (MIN)·T, whereN=2n (n is an integer of 2 or more) and M is an integer satisfying2n>M>2. With this configuration, the origin detection operation duringthe normal operation can be performed at N/M times the speed during theprocess adjustment.

Preferably, the judgment position is located at a position ½ cycle ofthe driving signal away from the reference position read out from thereference position storage.

Preferably, the judgment position is located at a position ½ cycle ofthe M/N periodic driving signal away from the reference position readout from the reference position storage. With these configurations, adistance between the judgment positions equals one cycle of the drivingsignal, which means that the origin (reference position) is includedbetween the judgment positions. Therefore, the origin can be reproducedsecurely.

Preferably, the lens position calculator designates the judgmentposition as a stopping position, and the lens position controller shiftsthe imaging lens to the stopping position before turning a power supplyof the lens driving apparatus off. With this configuration, the numberof times of judgment can be reduced, thus shortening the time ofreproducing the origin.

Preferably, the lens position calculator determines as a stoppingposition a position obtained by performing addition or subtraction tothe reference position, the lens controller shifts the imaging lens tothe stopping position before turning a power supply of the lens drivingapparatus off, and the stopping position is a position ½ cycle of thedriving signal away from the reference position.

Preferably, the lens position calculator determines as a stoppingposition a position obtained by performing addition or subtraction tothe reference position, the lens controller shifts the imaging lens tothe stopping position before turning a power supply of the lens drivingapparatus off, and the stopping position is a position ½ cycle of theM/N periodic driving signal away from the reference position. With theseconfigurations, only once judgment at first allows secure origindetection.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel. The lensposition calculator determines, based on inclination angle informationof the lens barrel output from the angular sensor, a correction distancecorresponding to a displacement from a reference angle. The lensposition calculator designates a position obtained by performingaddition or subtraction of the correction distance with respect to thejudgment position as a new judgment position, and designates the newjudgment position as the position where the output value of the positiondetection sensor is detected for the judgment. With this configuration,even when an inclination angle of the lens barrel is different betweenthe normal operation and the process adjustment and a position of achange in the photosensor output level varies therebetween, a variationin the origin detection can be prevented.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel. The lensposition controller controls a position of the imaging lens based oncorrection position information that is based on information of thereference position and inclination angle information of the lens barreloutput from the angular sensor.

Preferably, the lens position calculator determines as an upper endposition of the imaging lens a phase of the driving signal when theoutput value of the position detection sensor reaches a threshold valuein a state of the lens barrel facing upward, determines as a lower endposition of the imaging lens a phase of the driving signal when theoutput value of the position detection sensor reaches a threshold valuein a state of the lens barrel facing downward, and calculates thereference position based on the upper end position and the lower endposition. With this configuration, even when an orientation of the lensbarrel is different between the normal operation and the processadjustment, a variation in the origin detection can be prevented.

Preferably, the lens position calculator calculates an intermediateposition between the upper end position and the lower end position asthe reference position.

Preferably, the lens position calculator determines as an upper or alower end position of the imaging lens a phase of the driving signalwhen the output value of the position detection sensor reaches athreshold value in a state of the lens barrel facing upward or downward,and calculates the reference position by performing addition orsubtraction of a predetermined distance with respect to the upper or thelower end position. With this configuration, even when an orientation ofthe lens barrel is different between the normal operation and theprocess adjustment, a variation in the origin detection can beprevented. This configuration is suitable for an imaging apparatus whosevariation in origin detection due to attitude differences is specifiedby specifications.

Preferably, the lens driving apparatus further includes a temperaturesensor that detects a temperature of the lens barrel. The lens positioncalculator determines, based on temperature information of the lensbarrel output from the temperature sensor, a correction distancecorresponding to a displacement from a reference temperature. The lensposition calculator designates a position obtained by performingaddition or subtraction of the correction distance with respect to thejudgment position as a new judgment position, and designates the newjudgment position as the position where the output value of the positiondetection sensor is detected for the judgment. With this configuration,even when a temperature of the lens barrel is different between thenormal operation and the process adjustment and a position of a changein the photosensor output level varies therebetween, a variation in theorigin detection can be prevented.

Preferably, the lens driving apparatus further includes a temperaturesensor that detects a temperature of the lens barrel. The lens positioncontroller controls a position of the imaging lens based on correctionposition information that is based on information of the referenceposition and temperature information of the lens barrel output from thetemperature sensor.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel and atemperature sensor that detects a temperature of the lens barrel. Thelens position calculator determines, based on inclination angleinformation of the lens barrel output from the angular sensor, an anglecorrection distance corresponding to a displacement from a referenceangle, and determines, based on temperature information of the lensbarrel output from the temperature sensor, a temperature correctiondistance corresponding to a displacement from a reference temperature.The lens position calculator designates a position obtained byperforming addition or subtraction of a total distance of the anglecorrection distance and the temperature correction distance with respectto the judgment position as a new judgment position, and designates thenew judgment position as the position where the output value of theposition detection sensor is detected for the judgment. With thisconfiguration, even when an inclination angle and a temperature of thelens barrel are different between the normal operation and the processadjustment and a position of a change in the photosensor output levelvaries therebetween, a variation in the origin detection can beprevented.

According to the second lens driving apparatus of the present invention,a threshold value of the output value of the position detection sensorthat is used as the reference of the judgment during the normaloperation is made a value different from the threshold value of theprocess adjustment. The reference position is detected in such a manner,so that the generation of detection errors in origin, resulting from avariation in mechanism and electrical properties of a lens unit, can beprevented.

In the second lens driving apparatus of the present invention,preferably, assuming that a time of one cycle of the driving signal thatdrives the driver for determining the reference position is T, a drivingsignal that drives the driver for determining the reference positionagain is a 1/N periodic driving signal whose one cycle is T/N (N is aninteger of 2 or more). With this configuration, the origin detectionoperation during the normal operation can be performed at N times thespeed during the process adjustment.

Preferably, the second threshold value is a value within a range of anoutput value of the position detection sensor between the referenceposition and a position one cycle of the driving signal away from thereference position. Preferably, the second threshold value is an outputvalue of the position detection sensor at a position ½ cycle of thedriving signal away from the reference position. With theseconfigurations, a section between the judgment positions that has theoutput value of the position detection sensor corresponding to thesecond threshold value always exists, and therefore the origin can bereproduced securely.

Preferably, the lens position calculator designates the judgmentposition as a stopping position, and the lens position controller shiftsthe imaging lens to the stopping position before turning a power supplyof the lens driving apparatus off. With this configuration, the numberof times of judgment can be reduced, thus shortening the time ofreproducing the origin.

Preferably, the lens position calculator designates as a stoppingposition a judgment position that is an immediately preceding of ajudgment position corresponding to the reference position determinedagain, and the lens position controller shifts the imaging lens to thestopping position before turning a power supply of the lens drivingapparatus off. With this configuration, only once judgment at firstallows secure origin detection.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel. The lensposition calculator determines, based on inclination angle informationof the lens barrel output from the angular sensor, a correction distancecorresponding to a displacement from a reference angle. The lensposition calculator designates a position obtained by performingaddition or subtraction of the correction distance with respect to thejudgment position as a new judgment position, and designates the newjudgment position as the position where the output value of the positiondetection sensor is detected for the judgment. With this configuration,even when an inclination angle of the lens barrel is different betweenthe normal operation and the process adjustment and a position of achange in the photosensor output level varies therebetween, a variationin the origin detection can be prevented.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel. The lensposition controller controls a position of the imaging lens based oncorrection position information that is based on information of thereference position and inclination angle information of the lens barreloutput from the angular sensor.

Preferably, the lens position calculator determines as an upper endposition of the imaging lens a phase of the driving signal when theoutput value of the position detection sensor reaches the firstthreshold value in a state of the lens barrel facing upward, determinesas a lower end position of the imaging lens a phase of the drivingsignal when the output value of the position detection sensor reachesthe first threshold value in a state of the lens barrel facing downward,and calculates the reference position based on the upper end positionand the lower end position. With this configuration, even when anorientation of the lens barrel is different between the normal operationand the process adjustment, a variation in the origin detection can beprevented.

Preferably, the lens position calculator calculates an intermediateposition between the upper end position and the lower end position asthe reference position.

Preferably, the lens position calculator determines as an upper or alower end position of the imaging lens a phase of the driving signalwhen the output value of the position detection sensor reaches the firstthreshold value in a state of the lens barrel facing upward or downward,and calculates the reference position by performing addition orsubtraction of a predetermined distance with respect to the upper or thelower end position. With this configuration, even when an orientation ofthe lens barrel is different between the normal operation and theprocess adjustment, a variation in the origin detection can beprevented. This configuration is suitable for an imaging apparatus whosevariation in origin detection due to attitude differences is specifiedby specifications.

Preferably, the lens driving apparatus further includes a temperaturesensor that detects a temperature of the lens barrel. The lens positioncalculator determines, based on temperature information of the lensbarrel output from the temperature sensor, a correction distancecorresponding to a displacement from a reference temperature. The lensposition calculator designates a position obtained by performingaddition or subtraction of the correction distance with respect to thejudgment position as a new judgment position, and designates the newjudgment position as the position where the output value of the positiondetection sensor is detected for the judgment. With this configuration,even when a temperature of the lens barrel is different between thenormal operation and the process adjustment and a position of a changein the photosensor output level varies therebetween, a variation in theorigin detection can be prevented.

Preferably, the lens driving apparatus further includes a temperaturesensor that detects a temperature of the lens barrel. The lens positioncontroller controls a position of the imaging lens based on correctionposition information that is based on information of the referenceposition and temperature information of the lens barrel output from thetemperature sensor.

Preferably, the lens driving apparatus further includes an angularsensor that detects an inclination angle of the lens barrel and atemperature sensor that detects a temperature of the lens barrel. Thelens position calculator determines, based on inclination angleinformation of the lens barrel output from the angular sensor, an anglecorrection distance corresponding to a displacement from a referenceangle, and determines, based on temperature information of the lensbarrel output from the temperature sensor, a temperature correctiondistance corresponding to a displacement from a reference temperature.The lens position calculator designates a position obtained byperforming addition or subtraction of a total distance of the anglecorrection distance and the temperature correction distance with respectto the judgment position as a new judgment position, and designates thenew judgment position as the position where the output value of theposition detection sensor is detected for the judgment. With thisconfiguration, even when an inclination angle and a temperature of thelens barrel are different between the normal operation and the processadjustment and a position of a change in the photosensor output levelvaries therebetween, a variation in the origin detection can beprevented.

According to the imaging apparatus of the present invention, the motorcontrol unit is provided in the camera main body, and therefore thecircuit configuration of the lens barrel can be simplifiedsignificantly, thus making the lens barrel compact and reducing a cost.Further, since the control information of the focus lens in a lensbarrel is stored in the storage in the lens barrel, the focus lens canbe controlled precisely irrespective of the types of the lens barrels.

The lens barrel of the present invention is on the precondition of beingused for a camera main body provided with a motor control unit.Therefore, the circuit configuration of the lens barrel can besimplified significantly, thus making the lens barrel compact andreducing a cost. Further, since the control information of the focuslens in a lens barrel is stored in the storage in the lens barrel, bytransmitting this control information to the motor control unit of thecamera main body, the motor control unit can obtain control informationdepending on the type of the lens barrel, and therefore the focus lenscan be controlled precisely.

According to the present invention, the camera main body is providedwith the motor control unit. Therefore, the motor control unit can beeliminated from the lens barrel, thus simplifying the circuitconfiguration of the lens barrel and making the lens barrel compact andreducing a cost.

In the first imaging apparatus of the present invention, the motordriver outputs a periodic driving signal in accordance with receivedinformation output from the motor controller, and the motor shifts thefocus lens in the direction of the optical axis in accordance with theoutput driving signal. The lens barrel further includes a positiondetection sensor whose output value varies with a position of the focuslens. The motor controller determines as a reference position of thefocus lens a phase of the driving signal when an output value of theposition detection sensor reaches a threshold value, and transfersinformation of the reference position via the second and the first datatransmitter/receptor so as to allow the information of the referenceposition to be stored as information in the information table of thestorage. With this configuration, information concerning a referenceposition stored beforehand in the information table during the processadjustment can be used as information setting a reference position againduring the normal operation.

Preferably, the motor controller determines as a judgment position aposition obtained by performing addition or subtraction with respect tothe reference position read out from the storage via the first and thesecond data transmitter/receptor, detects an output value of theposition detection sensor via the first and the second datatransmitter/receptor at a timing in synchronization with the drivingsignal that drives the motor driver and at the judgment position, andjudges whether the output value of the position detection sensor at thejudgment position reaches the threshold value or not, so as to determinethe reference position again. With this configuration, a referenceposition determined during the process adjustment is not detecteddirectly during the normal operation. Instead, at a judgment positiondifferent from the reference position, a reference position is detectedby judgment. Therefore, the generation of detection errors in origin,resulting from a variation in mechanism and electrical properties of alens unit, can be prevented.

Preferably, the judgment position is located at a position ½ cycle ofthe driving signal away from the reference position read out from thestorage. With this configuration, a distance between the judgmentpositions equals one cycle of the driving signal, which means that thereference position is included between the judgment positions.Therefore, the origin can be reproduced securely.

Preferably, the information table includes at least one of informationon the number of magnetic poles of the motor, information on a rotationresolution of the motor, information on a driving voltage of the motorand information on a maximum driving rate of the motor.

Preferably, the imaging apparatus further includes a temperature sensor.The information table includes correction information by a temperatureon a position of the focus lens, and the motor controller corrects theposition of the focus lens in accordance with a temperature change basedon temperature information of the temperature sensor and the correctioninformation. With this configuration, even when the temperature changes,a focusing position can be kept.

Preferably, the imaging apparatus further includes an angular sensor.The information table includes correction information by an attitudeangle on a position of the focus lens, and the motor controller correctsthe position of the focus lens in accordance with an angle change basedon angle information of the angular sensor and the correctioninformation. With this configuration, even when an attitude anglechanges, a focusing position can be kept.

Preferably, the information table includes information on the operationcycle of the motor, and the information on the operation cycle isupdated in accordance with a movement distance or a movement time of thefocus lens from turning on of a power supply of the imaging apparatus tocompletion of the power supply. With this configuration, the informationon the operation cycle can be utilized as information relating to themaintenance such as a timing for replacing the motor.

Preferably, the motor is at least one selected from the group consistingof a stepping motor, a linear motor, an ultrasound motor, a motorconfigured with a smooth impact driving mechanism, an electrostaticmotor and a piezoelectric motor.

Preferably, parity is added to transmission/reception data between thefirst transmitter/receptor and the second transmitter/receptor. Withthis configuration, it can be confirmed whether thetransmission/reception data can be transmitted/received securely.

Preferably, the lens barrel further includes a position detection sensorwhose output value varies with a position of the focus lens. The motoris driven by a periodic driving signal. When the focus lens is shiftedin the direction of the optical axis in accordance with the drivingsignal, a phase of the driving signal when an output value of theposition detection sensor reaches a threshold value is designated as areference position of the focus lens, and information of the referenceposition is stored as information in the information table of thestorage. With this configuration, information concerning a referenceposition stored beforehand in the information table during the processadjustment can be used as information setting a reference position againduring the normal operation.

Preferably, the information table includes at least one of informationon the number of magnetic poles of the motor, information on a movementdistance resolution of the motor, information on a driving voltage ofthe motor and information on a maximum driving rate of the motor.

Preferably, the information table includes correction information by atemperature on a position of the focus lens. With this configuration,even when the temperature changes, a focusing position can be kept usingthe correction information of the focus lens position.

Preferably, the information table includes correction information by anattitude angle on a position of the focus lens. With this configuration,even when an attitude angle changes, a focusing position can be keptusing the correction information of the focus lens position.

Preferably, the information table can store information on operationcycle of the motor. With this configuration, the information on theoperation cycle can be utilized as information relating to themaintenance such as a timing for replacing the motor.

Preferably, the motor is at least one selected from the group consistingof a stepping motor, a linear motor, an ultrasound motor, a motorconfigured with a smooth impact driving mechanism, an electrostaticmotor and a piezoelectric motor.

Preferably, parity is added to transmission/reception data between thefirst transmitter/receptor and the second transmitter/receptor. Withthis configuration, it can be confirmed whether thetransmission/reception data can be transmitted/received securely.

According to the second imaging apparatus of the present invention, theorigins of the first lens unit and the second lens unit can be detectedusing a common position detector. Thus, the number of components can bedecreased, and the lens barrel can be miniaturized in the optical axisdirection and in the outer rim direction.

In the second imaging apparatus of the present invention, preferably,the position detector includes a member to be detected that movestogether with the second lens unit in the direction of the optical axisand a sensor that detects a position of the member to be detected in thedirection of the optical axis.

Preferably, the position of the first lens unit is detected by bringingthe first lens unit into contact with the second lens unit by shiftingthe first lens unit by the first driver, followed by movement of thesecond lens unit together with the first lens unit, and by detecting aposition of the member to be detected, which moves together with themovement, by means of the position detector.

Preferably, the position of the second lens unit is detected by shiftingthe first lens unit together with the second lens unit by the firstdriver, followed by shifting of the second lens unit by the seconddriver, and by detecting a position of the member to be detected, whichmoves together with the shifting of the second lens unit, by means ofthe position detector.

Preferably, the second lens unit is moveable along a supporting memberin the direction of the optical axis. Shifting of the second lens unitby the second driver is performed by way of a movement restriction unitthat is shifted by the second driver. Shifting of the second lens unitby the first driver is performed by way of a movement conveying unitthat moves to be linked with the first lens unit. The movementrestriction unit and the movement conveying unit both are disposedcloser to the supporting member.

Preferably, the position detector is a light-transmission type sensor,and the member to be detected is a photo-interruption member of thelight-transmission type sensor.

Preferably, the first lens unit is a zoom lens unit, and the second lensunit is a focus lens unit.

According to the third imaging apparatus of the present invention, evenin the case of the abnormal stopping where electric power is suppliedexternally and such power supply is shut off abruptly, for example, theorigin detection process can be performed smoothly and the apparatus canbe returned to the normal state when electric power is supplied again.

In the third imaging apparatus of the present invention, preferably,when electric power is supplied after the abnormal completion state, thefirst lens unit and the second lens unit are returned to the normalcompletion state in accordance with the information stored in thestorage, and the first lens unit is shifted at least by the first driverso as to perform the predetermined process operation for supplying theelectric power.

Preferably, the storage is a nonvolatile memory or a volatile memorydriven by a secondary power supply.

Preferably, the first lens unit is a zoom lens unit, and the second lensunit is a focus lens unit.

According to the driving apparatus of the present invention, the rotorcan be controlled for alignment accurately without using a sensor or thelike.

In the driving apparatus of the present invention, the calculation unitresets the origin by reading out the exciting position stored in theorigin storage unit, making the driver drive the stepping motor so as toadvance the exciting position so that the body to be driven is broughtcloser to the restriction end, and advance the exciting position from astate where the movement of the body to be driven is restricted by therestriction end to the position corresponding to the read out excitingposition, and resetting a value of the absolute position correspondingto this exciting position.

Preferably, the number of patterns of the exciting current supplied tothe stepping motor is n+1 from 0 to n (n+1 is an even number of 4 ormore). As the number of the patterns of the exciting current is advancedfrom 0 to n, the body to be driven approaches the restriction end,assuming that when restriction of movement of the body to be driven isstarted, the number of the pattern of the exciting current is n, and theexciting positions have the number of 0 to n corresponding to therespective numbers of the patterns of the exciting current, the numberof the exciting position corresponding to the origin is within a rangefrom (n+1)/2 to n−1.

Preferably, the driving apparatus further includes an offset storageunit that stores an offset movement amount corresponding to a movementamount from the exciting position stored in the origin storage unit to aspecific position that is a predetermined distance away from the exitingposition stored in the origin storage unit. The calculation unitcontrols, after resetting the origin of the body to be driven, thedriver so as to make the body to be driven move by the offset movementamount stored in the offset storage unit. With this configuration, thetime required to make the imaging apparatus ready for the operationafter turning the power on can be shortened.

Preferably, the body to be driven is a stop that controls a light amountof a subject light.

In the fourth lens driving apparatus of the present invention,preferably, the body to be driven is the lens supporting frame and astop that controls a light amount of a subject light.

The following describes one embodiment of the present invention, withreference to the drawings.

Embodiment 1

FIG. 1 includes a schematic diagram and a block diagram of a lensdriving apparatus according to Embodiment 1 of the present invention. InFIG. 1, numeral 1 denotes a lens barrel, 2 denotes a fixed lens fixed tothe lens barrel 1 and 3 denotes a zoom lens. The zoom lens 3 moves inthe optical axis direction so as to adjust a zoom magnification alongwith the rotation of a zoom ring 6 along the perimeter of the lensbarrel 1. Numeral 4 denotes a focus lens. When a motor 9 as a driverrotates, the focus lens 4 moves in the optical axis direction along alead screw with threads cut therein so as to enable the adjustment offocus.

In the example of FIG. 1, the motor 9 is a stepping motor that rotatesin accordance with a phase of a driving signal (exciting signal) for amotor coil output from a focus motor driving unit 11. Numeral 5 denotesan imaging device that converts an image of a subject captured throughthe fixed lens 2, the zoom lens 3 and the focus lens 4 into an electricsignal. Numeral 7 denotes a photo-interruption member that is fixed to aframe of the focus lens 4. As illustrated by the dotted lines of FIG. 1,the focus lens 4 is shifted toward the imaging device 5 so as tointerrupt a photosensor 8 as a position detection sensor by thephoto-interruption member 7, whereby the origin (reference position) ofthe focus lens 4 is detected.

Numeral 10 denotes a zoom ring position detection unit that detects arotation position of the zoom ring 6. The position is detected forexample using a pulse generated in accordance with the rotation of thezoom ring 6 or a linear position sensor whose resistance value varies inaccordance with the shifting distance of the zoom lens 3 in the opticalaxis direction. Numeral 12 denotes a signal processing unit thatgenerates image data and contrast information for performing focusadjustment based on an electric signal output from the imaging device 5.

Numeral 13 denotes a system control unit as lens position calculator.The system control unit 13 functions so as to provide an instruction fordriving the focus lens 4 to a focus motor control unit 15, which allowsa user to perform focus adjustment based on an image processed by thesignal processing unit 12, or to give an instruction for driving thefocus lens 4 so as to maximize the contrast based on the contrastinformation of the signal processing unit 12 for enabling automaticfocus adjustment (auto-focus function).

FIG. 2 is a detailed block diagram of the focus motor control unit 15shown in FIG. 1. In FIG. 2, the focus motor control unit 15 is made upof an exciting position counter 151, a tracking position control unit152 and an absolute position counter 153. The exciting position counter151 counts up or counts down the exciting position counter forcontrolling a phase of a driving signal for the motor 9 based on a focusmoving direction and moving step information output from the trackingposition control unit 152.

The tracking position control unit 152 outputs the focus movingdirection and the moving step information for controlling the positionof the focus lens 4 in accordance with instruction information from thesystem control unit 13 based on the zoom position information outputfrom the zoom ring position detection unit 10 and the focus positioninformation output from the absolute position counter 153.

In the above-stated configuration, the position of the focus lens 4 iscontrolled by the rotation of the motor 9. Further, the rotation of themotor 9 is controlled by a driving signal from the focus motor drivingunit 11 that receives a signal from the focus motor control unit 15.That is, the motor 9, the focus motor driving unit 11 and the focusmotor control unit 15 make up a lens position controller.

When the focus lens 4 is driven toward the imaging device 5 so that thephotosensor 8 is interrupted by the photo-interruption member 7, thuschanging a signal level of the photosensor to exceed a threshold valueunder a predetermined condition (or fall below a threshold value in somecircuit configurations), the system control unit 13 performs a processfor resetting the absolute position counter 153.

The system control unit 13 further includes an AD converter thatanalog-to-digital converts a signal output from the photosensor 8, andthe system control unit 13 handles the signal level of the photosensor 8as a digital value. For instance, an 8-bit AD converter with an input Drange of 3 V may be used. In this case, when an output level of thephotosensor changes from 0 V to 3 V, this output level can berepresented with digital values ranging from 0 to 255.

The absolute position counter 153 operates in synchronization with acounter value of the exciting position counter 151. The excitingposition counter 151 comes full circle to correspond to one cycle (360degrees) of a driving electrical angle of the motor 9, whereas theabsolute position counter 153 shows the absolute position with referenceto a value reset under a predetermined condition. Numeral 14 denotes anonvolatile memory, by which writing and reading operations with respectto the exciting position counter 151 can be conducted. As describedlater, the nonvolatile memory 14 serves as reference position storage.

The operation of the thus configured lens driving apparatus is describedbelow, with reference to FIG. 3. FIG. 3 is a drawing for explaining anorigin detection operation during the process adjustment according toEmbodiment 1. The “exciting position” shown in FIG. 3 corresponds to aphase of the driving signal, which represents a 3-bit counter value ofthe exciting position counter 151 obtained by dividing one cycle of 360degrees of a driving signal for the motor coil of the motor 9 outputfrom the focus motor driving unit 11 into 8 sections. This drawing showsa state where the exciting position is decreased one by one along withthe movement of the focus lens 4 to the imaging device 5 side.

The “A-phase current” and the “B-phase current” show current waveformsof the motor coil that the focus motor driving unit 11 outputs to themotor 9, and in this example the motor 9 has a two-phase coil with theA-phase and the B-phase. The A-phase current and the B-phase currenthave electrical angles different from each other by the phase of 90° (inthe case where one cycle of the current waveform is 360 degrees), andthe motor 9 is rotated by applying a current to the motor coil with theA-phase and the B-phase. In this drawing, the focus lens 4 moves to theimaging device 5 side while the A-phase current is 90° leading relativeto the B-phase current.

The “absolute position counter” represents a counter value of theabsolute position counter 153, and operates in synchronization with theexciting position. In the case where the exciting position is decreasedone by one, the absolute position counter also is decreased one by one.Herein, the absolute position counter sets a bit width so that the samevalue is not assigned to different positions in the movement range ofthe focus lens 4.

The “photosensor output level” shows the state where the output levelchanges as the focus lens 4 moves toward the imaging device 5 so thatthe photosensor 8 is interrupted by the photo-interruption member 7.

Referring now to FIGS. 3 and 4, the origin detection operation of thefocus lens 4 during the process adjustment is described morespecifically. FIG. 4 is a flowchart of the origin detection operationaccording to Embodiment 1 of the present invention, which shows anoperation flow described as a program in the system control unit 13.When the power is turned on, the process starts with “origin detectionadjustment start”.

In Step 101 the motor 9 as a focus motor is shifted to the origindetection direction (the direction of the imaging device 5) by one stepat a time. In this case, the exciting position counter 151 is decreasedone by one. More specifically, in response to an instruction from thesystem control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 102, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not. In the case of not exceeding,the process returns to Step 101 to make the motor 9 conduct the next onestep operation. In the case of exceeding, the process goes to Step 103,where the exciting position at the time of exceeding is substituted asP. In this case, the exciting position “4” is substituted as P. In Step104, P is stored as P_(O) in the nonvolatile memory 14. In Step 105, theabsolute position counter is reset. In FIG. 3, the position indicatedwith “0” shows the reset position.

Next, the origin detection operation of the focus lens 4 during thenormal operation is described, with reference to FIGS. 5 and 6. FIG. 5is a drawing for explaining the origin detection operation during thenormal operation according to Embodiment 1. FIG. 6 is a flowchart of theorigin detection operation during the normal operation according toEmbodiment 1, which shows an operation flow described as a program inthe system control unit 13. Since the exciting position, the A-phasecurrent, the B-phase current, the absolute position counter and thephotosensor output level shown in FIG. 5 are the same as those describedin FIG. 3, the explanations for the duplication are omitted.

In FIG. 6, when the power is turned on, the process starts with “origindetection start”. In Step 201, P_(O) is read out from the nonvolatilememory 14. In Step 202, Pd is calculated from the following formula (1):Pd=P _(O)−(exciting position one cycle)/2   (formula 1),

where (exciting position one cycle) is “8”. During the above-describedorigin detection operation for the focus lens 4 during the processadjustment, the value stored in the nonvolatile memory 14 is “4”.Therefore, in this example, Pd=4−8/2=0.

In Step 203, a judgment is made as to whether Pd is negative or not. Inthe case where Pd is 0 or positive, the process goes to the next Step204. In the case where Pd is negative, Pd=Pd+(exciting position onecycle) is calculated in Step 203 a, and then the process goes to thenext Step 204. When Pd is negative, there is no corresponding numericalvalue for the exciting position. However, the calculation in Step 203 aallows the exciting position Pd that differs by half cycle from P_(O) tobe determined.

In Step 204, the motor 9 is shifted by one step at one time to theorigin detection direction (the direction of the imaging device 5)(decrease the exciting position counter one by one). More specifically,in response to an instruction from the system control unit 13, theexciting position counter 151 is down-counted via the tracking positioncontrol unit 152. In accordance with this down-counting, the focus motordriving unit 11 rotates the motor 9 so as to shift the focus lens 4toward the imaging device 5.

In Step 205, a judgment is made as to whether the present excitingposition equals Pd (in this example, Pd=0) or not. In the case of notbeing equal, the process returns to Step 204 to make the motor 9 conductthe next one step operation. In the case of being equal, the processgoes to the next Step 206. In the example of FIG. 5, the positionsindicated by the judgment (n−2), the judgment (n−1) and the judgment (n)equal Pd (Pd=0) in the exciting position. In Step 206, a judgment ismade as to whether the photosensor output level exceeds a thresholdvalue or not at each of these positions.

Firstly, at the position of the judgment (n−2), a judgment is made as towhether the photosensor output level exceeds the threshold value or not.In the example of FIG. 5, it does not exceed the threshold value, andtherefore the process returns to Step 204 to make the motor 9 conductthe next one step operation. After the repetition of one step operation,at the position of the judgment (n−1), a judgment is made again as towhether the photosensor output level exceeds the threshold value or not.In the example of FIG. 5, it does not exceed the threshold value, andtherefore the process returns to Step 204 to make the focus motorconduct the next one step operation. After the repetition of one stepoperation, at the position of the judgment (n), a judgment is made againas to whether the photosensor output level exceeds the threshold valueor not. In the example of FIG. 5, it exceeds the threshold value. Inthis case, the process goes to Step 207, where the absolute positioncounter 153 is preset at —(exciting position one cycle)/2. Since(exciting position one cycle) in this example=8, the absolute positioncounter 153 is preset at “−4” (as shown in FIG. 5, the value of theabsolute position counter surrounded with the circle ◯).

Herein, the photosensor output level indicated by P2 in FIG. 5 shows alevel variation under the conditions of the mechanism and electricalproperties at the same operational environmental temperature andhumidity as those during the process adjustment. However, during thenormal operation in which the power may be turned on repeatedly, thephotosensor output level generates a variation different from P2 in therespective exciting positions as indicated by P1 and P3. This resultsfrom errors in looseness in the lens unit driving direction andvariations in mechanism and electrical properties due to a temperatureand humidity change in the operation environment.

In the present embodiment, in the origin detection operation during thenormal operation, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not at the judgment (n−2), thejudgment (n−1) and the judgment (n) shown in FIG. 5, as described above.From this, even when a variation occurs within the range from P1 to P3,the absolute counter 153 always is preset at “−4”, and when the absoluteposition counter is “0”, the exciting position of the motor 9 alwaysbecomes “4”, thus allowing the origin during the process adjustment tobe reproduced.

More specifically, the exciting position for each judgment is at theposition of Pd (Pd=0) as described above. Since Pd is a value calculatedfrom the above formula (1), this is located at a position different fromthe origin P_(O) (the position with the exciting position of “4”) by ahalf cycle. Thus, between the position of Pd and the next Pd, i.e.,between the judgment position and the next judgment position, theexciting position varies by one cycle, which always passes through theposition with the exciting position of “4”.

Although the position with the exciting position of “4” is locatedbetween one judgment position and the next judgment position, thisexciting position “4” is not the origin if none of the photosensoroutput levels exceed a threshold value. On the other hand, if thephotosensor output level at one judgment position does not exceed athreshold value but the photosensor output level at the next judgmentposition exceeds the threshold value, the exciting position “4” betweenthese judgment positions is the origin.

As described above, the exciting position at the judgment position islocated at a position different from the origin by half cycle.Therefore, if the absolute position counter 153 at the judgment positionwhere the photosensor output level exceeds a threshold value is presetat “−4”, the position with the absolute position counter of “0” can bethe origin obtained during the process adjustment.

If there is a variation in photosensor output level as indicated by P1and P3 of FIG. 5, the photosensor output level will exceed a thresholdvalue at a position other than the origin. Therefore, even if theposition with the photosensor output level exceeding a threshold valueis judged as the origin, that position is not the origin. According tothe present embodiment, there is no need to detect the origin directly,but if it can be detected that the photosensor output level at onejudgment position does not exceed a threshold value but the photosensoroutput level at the next judgment position exceeds the threshold value,the origin can be detected accurately.

Note here that a range of errors in looseness of the lens unit in thedriving direction and variations in mechanism and electrical propertiesdue to a temperature and humidity change in the operation environmentshould be within the exciting position one cycle.

In the example of the above-stated Step 202, (exciting position onecycle)/2 is subtracted from P_(O) as in the above-stated formula (1).However, (exciting position one cycle)/2 may be added as in thefollowing formula (2):Pd=P _(O)+(exciting position one cycle)/2.   (formula 2)

In this case, if Pd≧(exciting position one cycle) in Step 203, Pd iscalculated from the following formula 3 in Step 203 a. From this, theexciting position Pd can be determined so as to differ from P_(O) by ahalf cycle.Pd=Pd−(exciting position one cycle).   (formula 3)

For instance, in the present embodiment, P_(O)=4 and the excitingposition one cycle is 8. Therefore, the value of the above-statedformula (2) becomes 4+4=8, and this value can satisfy the relationshipof Pd≧exciting position one cycle. Thus, when Pd is determined from theformula (3), 8−8=0, which is the same result as that using the formula(1). In this way, the formula (2) can be used instead of the formula(1), which holds true for the respective embodiments that will bedescribed later.

FIG. 7 is a graph showing the relationship between the zoom position andthe focus position. L1 represents the relationship between the zoomposition and the focus position enabling the zoom operation whilekeeping the focus condition, when the distance from the front face ofthe fixed lens to the subject is set at 2 m, for example. L2 representsthe relationship between the zoom position and the focus positionenabling the zoom operation while keeping the focus condition, when thedistance from the front face of the fixed lens to the subject is set at1 m, for example.

T of the zoom position on the horizontal axis shows a telephoto side,and W shows a wide-angle side. Assuming that the distance from the frontface of the fixed lens to the subject is 1 m under the ideal conditionwithout deviation in origin detection of the focus, in the case wherethe focus position is determined on the T side (point A of the drawing),the zooming operation can be conducted while keeping the focus conditionalong the graph of L2 when the zoom position is shifted to the W side.

However, in the case where the focus position is determined on the Tside with the distance from the front face of the fixed lens to thesubject set at 2 m, this may agree with the point (point A of thedrawing) on the T side under the ideal condition when the distance fromthe front face of the fixed lens to the subject is 1 m, due to aninfluence of the deviation ΔX in origin detection. In such a case, whenthe zoom position is shifted to the W side, the zooming operation willbe conducted based on the graph L10 in which the focus position isdeviated from L1 by ΔX. Therefore, the focus position will be deviatedon the W side. According to the present invention, this does not occur,and the origin detection operation free from influences of errors inlooseness of the focus lens unit in the driving direction and variationsin mechanism and electrical properties due to a temperature and humiditychange in the operation environment can be realized. Therefore, theaccuracy in absolute position of the focus lens unit can be enhancedremarkably, and especially the present invention is effective for asystem performing a zooming operation while maintaining a focuscondition.

Embodiment 2

The following describes Embodiment 2 of the present invention.Embodiment 2 is the same as in Embodiment 1 in the configuration shownin FIG. 1 and FIG. 2 and the origin detection operation during theprocess adjustment described referring to FIG. 3 and FIG. 4.

Referring now to FIGS. 8 and 9, the origin detection operation of afocus lens 4 during the normal operation in Embodiment 2 is describedbelow. FIG. 8 is a drawing for explaining the origin detection operationduring the normal operation according to Embodiment 2. Since theexciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.8 are the same as those described in FIG. 3, the duplicate explanationsare omitted.

Embodiment 2 is different from Embodiment 1 in that the excitingposition is decreased by two at one time when the focus lens 4 isshifted to the imaging device 5 side. Therefore, an absolute positioncounter 153, which operates in synchronization with the excitingposition, also is decreased by two at one time. Herein, the absoluteposition counter sets a bit width so that the same value is not assignedto different positions in the movement range of the focus lens 4.

In Embodiment 1, the time for one cycle of the driving signal is thetime T for both of the process adjustment and the normal operation asshown in FIGS. 3 and 5. However, in Embodiment 2, the time for one cycleof the driving signal during the normal operation is T/2 as shown inFIG. 8. Thereby, Embodiment 2 enables the origin detection operationduring the normal operation at twice the speed of Embodiment 1.

FIG. 9 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 2, which shows an operationflow described as a program in the system control unit 13. When thepower is turned on, the process starts with “origin detection start”. InStep 301, P_(O) is read out from the nonvolatile memory 14. In Step 302,in accordance with the above-stated formula (1), Pd=P_(O)−(excitingposition one cycle)/2 is calculated, where (exciting position one cycle)is 8. Also in Embodiment 2, the example is explained where the valuestored in the nonvolatile memory 14 is “4” similarly to Embodiment 1.

Therefore, in this embodiment also, Pd=4−8/2=0. In Step 303, a judgmentis made as to whether Pd is negative or not. In the case where Pd is 0or positive, the process goes to the next Step 304. In the case where Pdis negative, Pd=Pd+(exciting position one cycle) is calculated in Step303 a, and then the process goes to the next Step 304. The reason forundergoing Step 303 a in the case of Pd being negative is the same asthe reason for undergoing Step 203 a of FIG. 6 in Embodiment 1.

In Step 304, the motor 9 is shifted by two steps at one time to theorigin detection direction (the direction of the imaging device 5)(decrease the exciting position counter by two at one time with therotation pitch S=2). Herein, the exciting position is set so as toinclude the above-obtained Pd (in this case, Pd=0).

More specifically, in response to an instruction from the system controlunit 13, the exciting position counter 151 is down-counted via thetracking position control unit 152. In accordance with thisdown-counting, the focus motor driving unit 11 rotates the motor 9 so asto shift the focus lens 4 toward the imaging device 5.

In Step 305, a judgment is made as to whether the present excitingposition equals Pd (in this example, Pd=0) or not. In the case of notbeing equal, the process returns to Step 304 to make the motor 9 conductthe next two-step operation. In the case of being equal, the processgoes to a judgment at the next Step 306.

The judgment positions are the positions indicated by the judgment(n−3), the judgment (n−2), the judgment (n−1) and the judgment (n) ofFIG. 8. In Step 306, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not. In the case of notexceeding, the process returns to Step 304 to make the focus motorconduct the next two-step operation. In the case of exceeding, theprocess goes to Step 307. At the time of exceeding, the absoluteposition counter 153 is preset at −(exciting position one cycle)/2.Herein, this is preset at “−4” because (exciting position one cycle)=8(as shown in FIG. 8, the value of the absolute position countersurrounded with the circle ◯).

Similarly to Embodiment 1, even when there is a variation in photosensoroutput level within the range from P1 to P3, the origin during theprocess adjustment can be reproduced securely. In addition to this,Embodiment 2 enables the origin detection operation during the normaloperation at twice the speed of Embodiment 1.

Incidentally, similarly to Embodiment 1, a range of errors in loosenessof the lens unit in the driving direction and variations in mechanismand electrical properties due to a temperature and humidity change inthe operation environment should be within the exciting position onecycle.

Embodiment 3

The following describes Embodiment 3 of the present invention. In thefollowing description, duplication of the configurations shown in FIG. 1and FIG. 2 described in Embodiment 1 is omitted. Embodiment 3 explainsthe example where the focus motor driving unit 11 of FIG. 1 drives themotor 9 to rotate by substantially sine wave driving (called alsomicrostep driving). Further, the exciting position counter 151 of FIG. 2is a 5-bit counter that comes full circle with the counter value of 32representing one cycle (360 degrees) of the driving electrical angle ofthe motor 9. The absolute position counter 153 operates insynchronization with the counter value of the exciting position counter151, and is preset or reset under a predetermined condition describedlater.

The operation is described below, with reference to FIG. 10. FIG. 10 isa drawing for explaining an origin detection operation during theprocess adjustment according to Embodiment 3. The “exciting position”shown in FIG. 10 corresponds to a phase of the driving signal, whichrepresents a 5-bit counter value for the exciting position counter 151obtained by dividing one cycle of 360 degrees of a driving signal forthe motor coil of the motor 9 output from the focus motor driving unit11 into 32 sections.

This drawing shows a state where the exciting position is decreased oneby one along with the movement of the focus lens 4 to the imaging device5 side. The “A-phase current” and the “B-phase current” show currentwaveforms in a substantially sine wave form of the motor coil that thefocus motor driving unit 11 outputs to the motor 9, and in this examplethe motor 9 has a two-phase coil with the A-phase and the B-phase. TheA-phase current and the B-phase current have electrical angles differentfrom each other by the phase of 90° (in the case where one cycle of thecurrent waveform is 360 degrees), and the motor 9 is rotated by applyinga current to the motor coil with the A-phase and the B-phase. In thisdrawing, the focus lens 4 moves to the imaging device 5 side while theA-phase current is 90° leading relative to the B-phase current.

Herein, the focus motor driving unit 11 is configured so as to output asubstantially sine wave formed current waveform by using a ROM table inwhich the relationship between the counter value of the excitingposition counter 151 and the driving current value is set beforehand,for example. The “absolute position counter” represents a counter valueof the absolute position counter 153, and operates in synchronizationwith the exciting position. In the case where the exciting position isdecreased one by one, the absolute position counter also is decreasedone by one. Herein, the absolute position counter sets a bit width sothat the same value is not assigned to different positions in themovement range of the focus lens 4.

The “photosensor output level” shows the state where the-output levelchanges as the focus lens 4 moves toward the imaging device 5 so thatthe photosensor 8 is interrupted by the photo-interruption member 7.

Referring now to FIGS. 4 and 10, the origin detection operation of thefocus lens 4 during the process adjustment is described morespecifically. Although FIG. 4 is a flowchart of the origin detectionoperation according to Embodiment 1, this flowchart is common toEmbodiment 3. However, since there are some different parts in settingthe conditions in each step, the following focuses on such differentparts from Embodiment 1.

When the power is turned on, the process starts with “origin detectionadjustment start”. In Step 101 the motor 9 as a focus motor is shiftedto the origin detection direction (the direction of the imaging device5) by one step at one time. In Step 102, a judgment is made as towhether the photosensor output level exceeds a threshold value or not.In the case of not exceeding, the process returns to Step 101 to makethe motor 9 conduct the next one step operation. In the case ofexceeding, the process goes to Step 103, where the exciting position atthe time of exceeding is substituted as P. In this case, the excitingposition “17” is substituted as P. In Step 104, P is stored as P_(O) inthe nonvolatile memory 14. In Step 105, the absolute position counter isreset. In FIG. 10, the position indicated with “0” shows the resetposition.

Next, the origin detection operation of the focus lens 4 during thenormal operation is described, with reference to FIGS. 9 and 11. FIG. 11is a drawing for explaining the origin detection operation during thenormal operation according to Embodiment 3. Although FIG. 9 is aflowchart of the origin detection operation according to Embodiment 2,this flowchart is common to Embodiment 3. However, since there are somedifferent parts in setting the conditions in each step, the followingfocuses on such different parts from Embodiments 1 and 2.

In FIG. 9, when the power is turned on, the process starts with “origindetection start”. In Step 301, P_(O) is read out from the nonvolatilememory 14. In Step 302, Pd is calculated from the following formula (1):Pd=P_(O)−(exciting position one cycle)/2. In this formula, (excitingposition one cycle) is “32”. During the above-described origin detectionoperation of the focus lens 4 during the process adjustment, the valuestored in the nonvolatile memory 14 is “17”. Therefore, in this example,Pd=17−32/2=1.

In Step 303, a judgment is made as to whether Pd is negative or not. Inthe case where Pd is 0 or positive, the process goes to the next Step304. In the case where Pd is negative, Pd=Pd+(exciting position onecycle) is calculated in Step 303 a, and then the process goes to thenext Step 304. When Pd is negative, there is no corresponding numericalvalue for the exciting position. However, the calculation in Step 303 aallows the exciting position Pd that differs by a half cycle from P_(O)to be determined.

In Step 304, the motor 9 is shifted by eight steps at one time to theorigin detection direction (the direction of the imaging device 5)(decrease the exciting position counter by eight at one time with therotation pitch S=8). As a result, the speed of the origin detectionoperation during the normal operation is eight times the speed duringthe process adjustment, and the driving cycle during the normaloperation becomes T/8, where T is the driving cycle during the processadjustment. Herein, the exciting position is set so as to include theabove-obtained Pd (in this case, Pd=1) similarly to the above-describedEmbodiment 2.

In Step 305, a judgment is made as to whether the present excitingposition equals Pd (in this example, Pd=1) or not. In the case of notbeing equal, the process returns to Step 304 to make the motor 9 conductthe next 16-step operation. In the case of being equal, the process goesto the next Step 306. In the example of FIG. 11, the positions indicatedby the judgment (n−3), the judgment (n−2), the judgment (n−1) and thejudgment (n) equal Pd (Pd=1) in the exciting position. In Step 306, ajudgment is made as to whether the photosensor output level exceeds athreshold value or not at each of these positions. Firstly, at theposition of the judgment (n−3), a judgment is made as to whether thephotosensor output level exceeds a threshold value or not. In theexample of FIG. 11, it does not exceed the threshold value, andtherefore the process returns to Step 304 to make the motor 9 conductthe next 16-step operation. After the repetition of 16-step operation,at the position of the judgment (n−2), a judgment is made again as towhether the photosensor output level exceeds the threshold value or not.In the example of FIG. 11, it does not exceed the threshold value, andtherefore the process returns to Step 304 to make the focus motorconduct the next 16-step operation. After the repetition of 16-stepoperation, at the position of the judgment (n), a judgment is made againas to whether the photosensor output level exceeds the threshold valueor not.

In the example of FIG. 11, it exceeds the threshold value. In this case,the process goes to Step 307, where the absolute position counter 153 ispreset at −(exciting position one cycle)/2. In this example, since(exciting position one cycle) =32, the absolute position counter 153 ispreset at “−16” (as shown in FIG. 11, the value of the absolute positioncounter surrounded with the circle ◯).

Herein, the photosensor output level indicated by P20 in FIG. 11 shows alevel variation under the conditions of the mechanism and electricalproperties at the same operational environmental temperature andhumidity as those during the process adjustment. However, during thenormal operation in which the power may be turned on repeatedly, thephotosensor output level generates a variation different from P20 in therespective exciting positions of the motor 9 as indicated by P10 andP30. This results from errors in looseness in the lens unit drivingdirection and variations in mechanism and electrical properties due to atemperature and humidity change in the operation environment.

In the present embodiment, in the origin detection operation during thenormal operation, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not at the judgment (n−3), thejudgment (n−2), the judgment (n−1) and the judgment (n) shown in FIG.11, as described above. From this, even when a variation occurs withinthe range from P10 to P30, the absolute counter 153 always is preset at“−16”, and when the absolute position counter is “0”, the excitingposition of the motor 9 always becomes “17”, thus allowing the originduring the process adjustment to be reproduced.

Similarly to Embodiment 1, even when there is a variation in photosensoroutput level within the range from P10 to P30, the origin during theprocess adjustment can be reproduced securely.

In addition to this, since the motor is driven to rotate bysubstantially sine wave driving in Embodiment 3, this embodiment allowsthe division number of one cycle of 360 degrees to be increased when thecounter value is set, thus increasing the bit number of the counter.

Thus, the origin of the focus lens during the process adjustment can bedetected with higher precision than in Embodiment 1, and even when theorigin detection operation during the normal operation is conducted at ahigher speed similarly to Embodiment 2, the origin during the processadjustment, detected with high precision, can be reproduced securely.Further, since the center value with respect to a variation occurringduring the normal operation can be determined precisely during theprocess adjustment, the design margin for the variation can be secured.

Incidentally, similarly to Embodiments 1 and 2, a range of errors inlooseness of the lens unit in the driving direction and variations inmechanism and electrical properties due to a temperature and humiditychange in the operation environment should be within the excitingposition one cycle.

Herein, assuming that the cycle of a driving signal for driving themotor when the reference position is determined during the processadjustment is T, the cycle T′ of a driving signal for the motor when thereference position is determined again during the normal operation canbe represented with the following formula (4):T′=(M/N)·T   (formula 4),

where N=2n (n is an integer of 2 or more), M is an integer satisfying2n>M>2).

In Embodiment 3, the cycle of the motor driving waveform for the origindetection operation during the normal operation is described as ⅛ of thecycle of the motor driving waveform for the origin detection operationduring the process adjustment (i.e., M=1, N=8). However, the cycle ofthe motor driving waveform for the origin detection operation during thenormal operation may be 3/32 (i.e., M=3, N=32). More specifically, inFIG. 20, instead of advancing the exciting position of 1→25→17→9→1, thismay be advanced as in 1→22→11→1.

Further, in Embodiment 3, the motor driving is described assubstantially sine wave driving. However, this embodiment is applicableto the driving method of substantially sine wave driving by PWM.

Embodiment 4

The following describes Embodiment 4 of the present invention.Embodiment 4 is the same as in Embodiment 1 in the configuration shownin FIG. 1 and FIG. 2 and the origin detection operation during theprocess adjustment described referring to FIG. 3 and FIG. 4.

Referring now to FIGS. 12 and 13, the origin detection operation of afocus lens 4 during the normal operation in Embodiment 4 is describedbelow. FIG. 12 is a drawing for explaining the origin detectionoperation during the normal operation according to Embodiment 4. Sincethe exciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.12 are the same as those described in FIG. 3, the duplicate explanationsare omitted.

FIG. 13 is a flowchart of a power-off process according to Embodiment 4,which shows an operation flow described as a program in the systemcontrol unit 13. This drawing shows an example where when a power of amain body of an imaging device such as a still camera or a video movieis turned off by a main body switch (not illustrated), a transitionprocess to the power-off is performed.

When the power is turned off, the system control unit 13 starts theprocess with “power-off process start”. In Step 401, the motor 9 isshifted to the origin detection direction (the direction of the imagingdevice 5) by two steps at one time (decreases the exciting positioncounter by two at one time). Herein, the exciting position is set so asto include Pd (in this case, Pd=0) described in Embodiment 2. Morespecifically, in response to an instruction from the system control unit13, the exciting position counter 151 is down-counted via the trackingposition control unit 152. In accordance with this down-counting, thefocus motor driving unit 11 rotates the motor 9 so as to shift the focuslens 4 toward the imaging device 5.

In Step 402, if the counter value of the absolute position counter 153does not agree with the exciting position one cycle/2, the processreturns to Step 401 to make the focus motor conduct the next 2-stepoperation. In the case where they agree, the process goes to Step 403,where the power of the main body is turned off. In this case, since the(exciting position one cycle)=8, the power of the main body is turnedoff when “absolute position counter value”=4 (see FIG. 12).

Next, when the power is turned on by the main body switch, the operationis as follows: as described in Embodiment 2 with reference to FIG. 9,the process is conducted in accordance with the flowchart that startswith “origin detection start” when the power is turned on. Although thedescription of the midstream of the process is omitted because ofduplication, in Step 306 of FIG. 9, a judgment is made as to whether thephotosensor output level exceeds a threshold value or not, and thecounter value of the absolute position counter 153 is preset at “−4” (asshown in FIG. 12, the value of the absolute position counter surroundedwith the circle ◯).

As shown in FIG. 12, in the power-off transition process, the focusmotor is stopped immediately before the origin (immediately before thephotosensor output level exceeds the threshold value). Therefore, inEmbodiment 4, the first once judgment concerning the photosensor outputlevel is all that required to detect the origin when the power is tunedon. More specifically, since the position where the counter value of theabsolute position counter becomes “0” is the origin, the stoppingposition where the counter value agrees with the exciting position onecycle/2 is the judgment position on the preceding side between thejudgment positions sandwiching the origin. That is, the feature of thepresent embodiment resides in that the stopping position of the focusmotor during the power-off transition process is a judgment positionimmediately preceding the position for the final judgment of thephotosensor output level when the power is turned on next.

Thus the power-off transition process enables secure origin detectionsimply by the first once judgment of the photosensor output level evenwhen errors in looseness of the lens unit in the driving direction andvariations in mechanism and electrical properties due to a temperatureand humidity change in the operation environment occur before the poweris turned on next.

Incidentally, similarly to Embodiments 1, 2 and 3, a range of errors inlooseness of the lens unit in the driving direction and variations inmechanism and electrical properties due to a temperature and humiditychange in the operation environment should be within the excitingposition one cycle.

Embodiment 5

The following describes Embodiment 5 of the present invention.Embodiment 5 is the same as in Embodiment 1 in the configuration shownin FIG. 1 and FIG. 2. Referring now to FIGS. 14 and 15, the origindetection operation of a focus lens 4 during the process adjustment inEmbodiment 5 is described below.

FIG. 14 is a drawing for explaining the origin detection operationduring the process adjustment according to Embodiment 5. Since theexciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.14 are the same as those described in FIG. 3 of Embodiment 1, theduplicate explanations are omitted. Further, this embodiment is the sameas Embodiment 1 in that the exciting position is decreased one by onealong with the movement of the focus lens 4 to the imaging device 5side.

FIG. 15 is a flowchart of an origin detection operation during theprocess adjustment according to Embodiment 5, which shows an operationflow described as a program in the system control unit 13. This processstarts with “origin detection adjustment start” when the power is turnedon. In Step 501, on a liquid crystal display (not illustrated) showing aprocess adjustment menu, for example, “main body upward” is displayed. Alens 2 of the imaging apparatus is turned upward, and the process goesto the next Step 502.

In Step 502, the motor 9 is shifted to the origin detection direction(the direction of the imaging device 5) by one step at one time(decreases the exciting position counter one by one). More specifically,in response to an instruction from the system control unit 13, theexciting position counter 151 is down-counted via the tracking positioncontrol unit 152. In accordance with this down-counting, the focus motordriving unit 11 rotates the motor 9 so as to shift the focus lens 4toward the imaging device 5.

In Step 503, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not. In the case of not exceeding,the process returns to Step 502 to make the motor 9 conduct the next onestep operation. In the case of exceeding, the process goes to Step 504,where the exciting position at the time of exceeding is substituted asPu. In this case, the exciting position “6” is substituted as Pu.

Next, in Step 505, on the liquid crystal display (not illustrated)showing a process adjustment menu, for example, “main body downward” isdisplayed. The lens 2 of the imaging apparatus is turned downward, andthe process goes to the next Step 506. In Step 506, the motor 9 isshifted to the origin detection direction (the direction of the imagingdevice 5) by one step at one time (decreases the exciting positioncounter one by one).

In Step 507, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not. In the case of not exceeding,the process returns to Step 506 to make the motor 9 conduct the next onestep operation. In the case of exceeding, the process goes to Step 508,where the exciting position at the time of exceeding is substituted asPd.

In this case, the exciting position “2” is substituted as Pd. In Step509, the magnitude of Pd and Pu is judged. In this case, since Pu=6 andPd=2, the process goes to the next Step 510. In Step 510,P=INT((Pu+Pd)/2) is calculated, so that P=4 is determined. Incidentally,INT means to round up the figures after the decimal fractions. In Step511, a judgment is made as to whether P is smaller than 0 or not. Inthis example, since P=4, the process goes to the next Step 512 and P=4is stored as P_(O) in the nonvolatile memory.

In Step 513, the counter value of the absolute position counter 153 ispreset at −INT ((Pu—Pd)/2). The value of −INT ((Pu—Pd)/2) becomes −INT((6−2)/2)=−2. With this calculation, it can be calculated how far apartin exciting position the origin at the time of downward and the originof the intermediate between at the time of upward and downward are. Asshown in FIG. 14, assuming that the numerical value of the absoluteposition counter at the origin at the time of downward is −2 as thecalculated value (the value surrounded with the circle ◯), the countervalue of the absolute position counter 153 at the origin (excitingposition “4”) of the intermediate between at the time of upward anddownward becomes “0”.

Note here that the reason for generating a step in the photosensoroutput level when the attitude is changed from “upward state” to“downward state” in FIG. 14 is that the focus lens 4 is shifted to thedirection moving away from the imaging device 5 because of its ownweight and looseness (e.g., looseness of the rack for transferring thefocus lens 4 with the lead screw of the motor 9).

In the afore-mentioned example, the example where the origin detectionposition in the upward state is Pu=6 and the origin detection positionin the downward state is Pd=2, i.e., Pd<Pu is described. In this case,the intermediate position P can be determined from the formula of Step510 as described above. However, in the case of Pd>Pu, the intermediateposition P cannot be determined from the formula of Step 510. Forinstance, in the case of Pu=0 and Pd=4, the intermediate position P willbe 6 as is understood from the illustration of the exciting position inFIG. 14. However, according to the calculation using the formula of Step510, P=INT((0+4)/2)=2, which is different from P=6.

In such a case, the process may undergo Steps 509 a and 511 a, wherebythe correct intermediate position P can be determined. In theabove-stated example of Pu=0 and Pd=4, the process goes to Step 509 abecause Pd>Pu, where Pd=Pd−(exciting position one cycle) is calculated,from which Pd=−4 can be determined using “exciting position onecycle”=8. When P is determined by the formula of Step 510 using thisvalue of Pd, P=INT((0−4)/2)=−2. In this case, since P<0 in Step 511, theprocess goes to Step 511 a, where P=P+(exciting position one cycle) iscalculated, through which P=6 can be obtained. The reason for undergoingStep 511 a in the case where P is negative is the same as the reason forundergoing Step 203 a of FIG. 6 in Embodiment 1.

In this example, in Step 512, P=6 is stored as P_(O) in the nonvolatilememory 14. Next, in Step 513, using Pu=0, Pd=−4 calculated in Step 509a, −INT((Pu—Pd)/2)=−2 is obtained, so that “−2” is preset as the countervalue at the portion corresponding to the downward origin (Pd=4) of theabsolute position counter 153.

In this way, according to Embodiment 5, the origin stored in thenonvolatile memory 14 is the intermediate position of the originsdetected in the upward state and the downward state. Therefore ascompared with the case where the origin is adjusted withoutconsideration given to the difference due to attitude as described inEmbodiment 1, which might cause an upward attitude difference during theadjustment and cause a downward attitude difference during the normaloperation, for example, Embodiment 5 allows an error in lens positiondue to attitude difference to be improved to ½.

Further, in Embodiment 5, the example where the origin is detected inthe upward state firstly, and then the origin is detected in thedownward state is described. However, if, considering looseness, theposition in the upward state is farther away from the origin than in thedownward state, the origin may be detected in the downward statefirstly, followed by the origin detection in the upward state.

Further, in an imaging device in which a variation in origin detectionposition due to attitude difference is specified as a specification, theorigin may be detected in either the upward state or the downward state,and the position deviated from the detected position by half of thespecification may be set as the origin, whereby the same effects can beobtained.

The present embodiment is on the precondition that there is a variationin origin detection position due to the attitude difference of a lensbarrel. However, if the accuracy of a lens barrel can be secured so thata variation in origin detection position due to the attitude differenceof a lens barrel can be ignored, the configuration of the above-statedEmbodiments 1 to 4 may be adopted.

Embodiment 6

The following describes Embodiment 6 of the present invention. FIG. 16includes a schematic diagram and a block diagram of a lens drivingapparatus according to Embodiment 6. In FIG. 16, the same numerals areassigned to the same configurations as in FIG. 1 so as to omit theirdetailed explanations. The lens driving apparatus shown in FIG. 16includes a temperature sensor 16 and an angular sensor 17 in addition tothe lens driving apparatus of FIG. 1.

The temperature sensor 16 is provided in the lens barrel 1 or in theimaging apparatus main body (not illustrated), which is a sensor fordetecting a temperature, and a thermistor or the like is used therefor.The angular sensor 17 is provided in the lens barrel 1 or in the imagingapparatus main body (not illustrated), which is a sensor for detectingthe inclination of the lens barrel or the imaging apparatus main body.

FIG. 17 shows one example of angular detection by the angular sensor 17.The example of FIG. 17 shows that a voltage output from the angularsensor 17 is set at 0 when the lens barrel 1 or the imaging apparatus isin a horizontal position, and the output voltage varies in accordancewith the attitude angle.

Incidentally, the angular sensor 17 may be an inclination sensor thatdetects three positions of the lens barrel 1 or the imaging apparatusmain body including upward, downward and horizontal. In the presentembodiment, the focus motor control unit 15 has the same configurationas that of Embodiment 1 shown in FIG. 2.

Referring now to FIGS. 18 and 19, an origin detection operation by thefocus lens 4 during the normal operation in Embodiment 6 will bedescribed below. FIG. 18 is a drawing for explaining an origin detectionoperation during the normal operation according to Embodiment 6. FIG.18(a) is intended to show the state where the temperature is higher thana room temperature and the lens 2 of the lens barrel 1 faces upward, andFIG. 18(b) is intended to show the state where the temperature is lowerthan a room temperature and the lens 2 of the lens barrel 1 facesdownward.

Since the exciting position, the A-phase current, the B-phase current,the absolute position counter and the photosensor output level shown inFIG. 18 are the same as those described in FIG. 3 of Embodiment 1, theexplanations for the duplication are omitted. Further, the excitingposition is decreased by two at one time along with the movement of thefocus lens 4 to the imaging device 5 side, which is similar to theexample of FIG. 8 of Embodiment 2.

FIG. 19 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 6, which shows an operationflow described as a program in the system control unit 13. When thepower is turned on, the process starts with “origin detection start”. InStep 601, P_(O) is read out from the nonvolatile memory 14. In Step 602a, Pd=P_(O)−(exciting position one cycle)/2 is calculated. Herein,(exciting position one cycle) equals 8. During the origin detectionoperation of the focus lens 4 during the process adjustment, the valuestored in the nonvolatile memory 14 is “4”, which is similar toEmbodiment 1. Therefore, the result is Pd=4−8/2=0.

In Step 602 b, in accordance with the information output from thetemperature sensor 16 and the angular sensor 17, a correction value ΔPdis added to Pd. In the case where the lens 2 of the lens barrel 1 facesupward, the focus lens 4 moves closer to the imaging device 5 ascompared with the horizontal position due to its own weight andlooseness (e.g., looseness of the rack for transferring the focus lens 4with the lead screw of the motor 9). Moreover, in the case where thetemperature is higher than a room temperature and the photo-interruptionmember 7 has a thermal expansion coefficient larger than those of thelens barrel 1 and the motor 9, the photo-interruption member 7 movescloser to the photosensor 8.

For those reasons, as shown by P4 of the photosensor output level ofFIG. 18(a), the timing when the photosensor output level changes at thetime of the origin detection becomes earlier than the photosensor outputlevel P2 that shows the case where the lens is in a horizontal positionat a room temperature. In this case, an example where an error occurringdue to the temperature increase from a room temperature corresponds toone step of the exciting position of the motor 9 and an error occurringwhen the imaging apparatus in a horizontal position is made to faceupward corresponds to one step of the exciting position of the motor 9,whereby an error corresponding to two steps in total occurs, is shown.

Therefore, since ΔPd=2, Pd2=2 is calculated in Step 602 b. In Step 603,a judgment is made as to whether Pd2 is negative or not. In the casewhere Pd2 is 0 or positive, the process goes to the next Step 604. Inthe case where Pd is negative, Pd=Pd+(exciting position one cycle) iscalculated in Step 603 a, and then the process goes to the next Step604. The reason for undergoing Step 603 a in the case of Pd beingnegative is the same as the reason for undergoing Step 203 a of FIG. 6in Embodiment 1.

In Step 604, the motor 9 is shifted by two steps at one time to theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter by two at one time). Herein,the exciting position is set so as to include the above-obtained Pd2 (inthis case, Pd2=2). More specifically, in response to an instruction fromthe system control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 605, a judgment is made as to whether the present excitingposition equals Pd2 (in this example, Pd2=2) or not. In the case of notbeing equal, the process returns to Step 602 b to make the motor 9conduct the next two-step operation. In the case of being equal, theprocess goes to the next Step 606.

The positions with Pd2=2 are positions indicated with the judgment(n−2), the judgment (n−1) and the judgment (n) shown in FIG. 18(a).Since the exciting position is 2 at these judgment positions, this isthe position advancing by two steps from the exciting position 0 thatshows a position before adding the correction value (i.e., a positionmoving away from the imaging device 5). Therefore, the judgment at thesejudgment positions can be substantially equal to the case where thephotosensor output level P2 for the lens in a horizontal position at aroom temperature is detected at a position where the exciting positionis 0.

In Step 606, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not at the above-stated judgmentpositions. In the case of not exceeding, the process returns to Step 602b to make the focus motor conduct the next two-step operation. In thecase of exceeding, the process goes to Step 607. At the time ofexceeding, the absolute position counter 153 is preset at −(excitingposition one cycle)/2+ΔPd. Herein, this is preset at “−2” because(exciting position one cycle)=8 and ΔPd=2 (as shown in FIG. 18(a), thevalue of the absolute position counter surrounded with the circle ◯).

Note here that the explanations for FIG. 9 of Embodiment 2 show theexample where, if the conditions are not satisfied in Step 305 or Step306, the process returns to Step 304. On the contrary, Embodiment 6shows the example where the process returns to Step 602 b. This isbecause according to Embodiment 6 in the case where a temperaturechanges or the attitude difference changes during the origin detectionoperation, a position for judging whether the photosensor output levelexceeds a threshold value or not is changed successively.

The following describes the case where the lens 2 of the lens barrel 1faces downward and the temperature is lower than a room temperature,with reference to FIG. 18(b) and FIG. 19. In the case where the lens 2of the lens barrel 1 faces downward, the focus lens 4 moves away fromthe imaging device 5 as compared with the horizontal position due to itsown weight and looseness (e.g., looseness of the rack for transferringthe focus lens 4 with the lead screw of the motor 9). Moreover, in thecase where the temperature is lower than a room temperature and thephoto-interruption member 7 has a thermal expansion coefficient largerthan those of the lens barrel 1 and the motor 9, the photo-interruptionmember 7 moves away from the photosensor 8.

For those reasons, as shown by P5 of the photosensor output level ofFIG. 18(b), the timing when the photosensor output level changes at thetime of the origin detection becomes later than the photosensor outputlevel P2 that shows the case where the lens is in a horizontal positionat a room temperature. In this case, an example where an error occurringdue to the temperature decrease from a room temperature corresponds toone step of the exciting position of the motor 9 and an error occurringwhen the imaging device in a horizontal position is made to facedownward corresponds to one step of the exciting position of the motor9, whereby an error corresponding to two steps in total occurs, isshown.

Therefore, since ΔPd=−2, Pd2=−2 is calculated in Step 602 b. In Step603, a judgment is made as to whether Pd2 is negative or not. In thecase where Pd2 is negative, Pd2=Pd2+(exciting position one cycle) iscalculated in Step 603 a, and then the process goes to the next step. Inthe case where Pd2 is 0 or positive, the process goes to the next step.In this case, the resultant Pd2 is 6, because −2+8=6.

In Step 604, the motor 9 is shifted by two steps at one time to theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter by two at one time). Herein,the exciting position is set so as to include the above-obtained Pd2 (inthis case, Pd2=6). More specifically, in response to an instruction fromthe system control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 605, a judgment is made as to whether the present excitingposition equals Pd2 (in this example, Pd2=6) or not. In the case of notbeing equal, the process returns to Step 602 b to make the motor 9conduct the next two-step operation. In the case of being equal, theprocess goes to the next Step 606. The positions with Pd2=6 arepositions indicated with the judgment (n−3), the judgment (n−2) and thejudgment (n−1) shown in FIG. 18(b). Since the exciting position is 6 atthese judgment positions, this is the position behind by two steps fromthe exciting position 0 that shows a position before adding thecorrection value (i.e., a position moving closer to the imaging device5). Therefore, the judgment at these judgment positions can besubstantially equal to the case where the photosensor output level P2for the lens in a horizontal position at a room temperature is detectedat a position where the exciting position is 0.

In Step 606, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not at the above-stated judgmentpositions. In the case of not exceeding, the process returns to Step 602b to make the focus motor conduct the next two-step operation. In thecase of exceeding, the process goes to Step 607. At the time ofexceeding, the absolute position counter 153 is preset at −(excitingposition one cycle)/2+ΔPd.

Herein, this is preset at “−6” because (exciting position one cycle)=8and ΔPd=−2 (as shown in FIG. 18(b), the value of the absolute positioncounter surrounded with the circle ◯). Note here that the explanationsfor FIG. 9 of Embodiment 2 show the example where if the conditions arenot satisfied in Step 305 or Step 306, the process returns to Step 304.On the contrary, Embodiment 6 shows the example where the processreturns to Step 602 b. This is because in the case where a temperaturechanges or the attitude difference changes during the origin detectionoperation, a position for judging whether the photosensor output levelexceeds a threshold value or not is changed successively.

The photosensor output level indicated by “P2” in FIG. 18 shows a levelvariation under the conditions of the mechanism and electricalproperties at the same operational environmental temperature andhumidity as those during the process adjustment. However, during thenormal operation in which the power may be turned on repeatedly, avariation occurs in the position of a level change in accordance withthe exciting positions of the motor 9, as indicated by “P4” and “P5”.This results from errors in looseness in the lens unit driving directionand variations in mechanism and electrical properties due to atemperature change in the operation environment.

In Embodiment 6, however, in the origin detection operation during thenormal operation, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not at the respective judgmentpositions shown in FIG. 18. Therefore, even when a variation occurswithin the range from “P4” to “P5”, the exciting position of the motor 9always becomes “4” when the counter value of the absolute counter 153 is“0”, thus allowing the origin during the process adjustment to bereproduced as described in Embodiment 1.

The above-description shows the example using the temperature sensor andthe angular sensor. However, the use of a humidity sensor also enablesthe improvement of accuracy by improving an error occurring due to adifference in hygroscopic coefficient of the lens barrel and the lens.Further, Embodiment 6 allows the origin detection operation during thenormal operation conducted at twice the speed of Embodiment 1.

Further, if errors in looseness in the lens unit driving direction andvariations in mechanism and electrical properties due to a temperatureand humidity change in the operation environment can be detected using atemperature sensor and an angular sensor, the correction is possibleeven when these errors exceed the range of the exciting position onecycle.

FIG. 20 is a graph showing a relationship between the zoom position andthe focus position according to Embodiment 6. L1 represents therelationship between the zoom position and the focus position enablingthe zoom operation while keeping the focus condition, when the distancefrom the front face of the fixed lens to the subject is set at 2 m, forexample.

“T” of the zoom position on the horizontal axis shows a telephoto side,and “W” shows a wide-angle side. Assuming that the distance from thefront face of the fixed lens to the subject is 2 m under the idealcondition without deviation in origin detection of the focus, in thecase where the focus position is determined on the “T” side, the zoomingoperation can be conducted while keeping the focus condition along thegraph of L1 when the zoom position is shifted to the “W” side.

Since the temperature sensor 16 and the angular sensor 17 of FIG. 16 canbe used to detect errors in looseness in the lens unit driving directionand variations in mechanism and electrical properties due to atemperature change in operation environment, the focus position may becorrected with consideration given to the origin correction amount ΔXshown in FIG. 20 after the detection of the origin.

This graph shows the example where the correction in the state at a hightemperature and facing downward is conducted, while the focus positionon the “T” side is located at the position of X0 in the state at a roomtemperature and in a horizontal position. At a high temperature,distances between lenses increase relative to the design values becauseof thermal expansion of the lens barrel 1, and accordingly the focuslens 4 has to be shifted to the imaging device 5 side. Further, in thestate of facing downward, the focus lens 4 moves away from the imagingdevice 5 as compared with in the horizontal position due to its ownweight and looseness.

Therefore, assuming that the total position correction amount of thefocus lens 4 in the state at a high temperature and facing downward isΔX, X0−ΔX is determined so as to correct the position of the focus lens4 from the origin, whereby a zooming operation can be conducted whilemaintaining the focusing condition from the “T” side to the “W” side.

Herein, Embodiment 6 explains the example with consideration given tothe case where angles and temperatures of the lens barrel differ betweenthe process adjustment and the normal operation. However, theseconfigurations are not always the optimum one. For instance, in the casewhere a variation in photosensor output level due to changes in angleand temperature is suppressed by the configuration of the lens barrel orthe like, the configurations of Embodiments 1 to 4 are suitable.

Although Embodiment 6 explains the example of having both of the angularsensor and the temperature sensor, the configuration having one of thesesensors also is possible. For instance, in the case where a variation ina changing position of the photosensor output level due to a temperaturechange does not pose a problem especially, the correction can beconducted using an angular sensor only.

Further, although Embodiment 6 shows the example where ΔPd is added inStep 602 b of FIG. 19, ΔPd may be subtracted.

In the above-stated Embodiments 2, 4 and 6, the example where at thetime of the origin detection operation during the normal operation thelens unit is driven at twice the speed of the process adjustment isshown. However, these examples are non-limiting, and the operation atfour times or more the speed also is possible. That is, in the casewhere a time of the driving signal one cycle is T during the processadjustment, a time of the driving signal one cycle during the normaloperation may be T′ in the above-stated formula (4), and a drivingsignal with M/N cycle may be output.

Further, in Embodiments 4 and 6, the driving signal one cycle may be thesame for the process adjustment and the normal operation.

Further, although the exciting positions obtained by dividing the cycleof the driving signal of the motor into 8 and 32 sections are describedabove, these embodiments are not limited by the division number. Forexample, division into 4 and 16 sections may be set depending on therequired accuracy.

Further, the above-described embodiments explain the example using astepping motor as the driver. However, this may be other motors as longas an exciting signal of the motor has periodicity, and a linear motorfor example may be used.

Embodiment 7

The following describes Embodiment 7 of the present invention. A drivingapparatus according to Embodiment 7 also has the configuration shown inFIGS. 1 and 2. An operation thereof will be described below, withreference to FIG. 21. FIG. 21 is a drawing for explaining an origindetection operation during the process adjustment according toEmbodiment 7. The “exciting position” shown in FIG. 21 corresponds to aphase of the driving signal, which represents a 3-bit counter value forthe exciting position counter 151 obtained by dividing one cycle of 360degrees of a driving signal for the motor coil of the motor 9 outputfrom the focus motor driving unit 11 into 8 sections. This drawing showsa state where the exciting position is decreased one by one along withthe movement of the focus lens 4 to the imaging device 5 side.

The “A-phase current” and the “B-phase current” show current waveformsof the motor coil that the focus motor driving unit 11 outputs to themotor 9, and in this example the motor 9 has a two-phase coil with theA-phase and the B-phase. The A-phase current and the B-phase currenthave electrical angles different from each other by the phase of 90° (inthe case where one cycle of the current waveform is 360 degrees), andthe motor 9 is rotated by applying a current to the motor coil with theA-phase and the B-phase. In this drawing, the focus lens 4 moves to theimaging device 5 side while the A-phase current is 90° leading relativeto the B-phase current.

The “absolute position counter” represents a counter value of theabsolute position counter 153, and operates in synchronization with theexciting position. In the case where the exciting position is decreasedone by one, the absolute position counter also is decreased one by one.Herein, the absolute position counter sets a bit width so that the samevalue is not assigned to different positions in the movement range ofthe focus lens 4.

The “photosensor output level” shows the state where the output levelchanges as the focus lens 4 moves to the imaging device 5 side so thatthe photosensor 8 is interrupted by the photo-interruption member 7.Every time the exciting position of the motor 9 changes by one step, thephotosensor output level changes by 0.2 V, for example. In this case, inthe system control unit 13, it is recognized that the digital valuechanges by 17 using a built-in AD converter.

As described later, the system control unit 13 makes a judgment as towhether the photosensor output level exceeds a threshold value or not.For instance, a first threshold value can be 195 (about 2.3 V at the ADconversion input unit), which is a digital value after AD conversion,and a second threshold value can be 127 (about 1.5 V at the ADconversion input unit) as a digital value. The second threshold value isset at a value obtained by changing the exciting position of the motor 9by 4 steps with reference to the first threshold value, i.e., at a valueof the photosensor output level obtained by rotating the motor 9 by thehalf cycle (electrical angle of 180 degrees) of the exciting cycle(electrical angle of 360 degrees).

Referring now to FIGS. 21 and 22, the origin detection operation of thefocus lens 4 during the process adjustment is described morespecifically. FIG. 22 is a flowchart of the origin detection operationaccording to Embodiment 7 of the present invention, which shows anoperation low described as a program in the system control unit 13. Whenthe power is turned on, the process starts with “origin detectionadjustment start”.

In Step 111 the motor 9 as a focus motor is shifted to the origindetection direction (the direction of the imaging device 5) by one stepat one time. In this case, the exciting position counter 151 isdecreased one by one. More specifically, in response to an instructionfrom the system control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 112, a judgment is made as to whether the photosensor outputlevel exceeds a first threshold value or not. In the case of notexceeding, the process returns to Step 111 to make the motor 9 conductthe next one step operation. In the case of exceeding, the process goesto Step 113, where the exciting position at the time of exceeding issubstituted as P. In FIG. 21, since the photosensor output level exceedsthe first threshold value at the exciting position of “0”, the excitingposition of “0” is substituted as P.

In Step 114, P is stored as P_(O) in the nonvolatile memory 14. In Step115, the absolute position counter is reset. In FIG. 21, the positionindicated with “0” shows the reset position.

Next, the origin detection operation of the focus lens 4 during thenormal operation is described, with reference to FIGS. 23 and 24. FIG.23 is a drawing for explaining the origin detection operation during thenormal operation according to Embodiment 7. FIG. 24 is a flowchart ofthe origin detection operation during the normal operation according toEmbodiment 7, which shows an operation flow described as a program inthe system control unit 13. Since the exciting position, the A-phasecurrent, the B-phase current, the absolute position counter and thephotosensor output level shown in FIG. 23 are the same as thosedescribed in FIG. 21, the explanations for the duplication are omitted.

In FIG. 24, when the power is turned on, the process starts with “origindetection start”. In Step 211, P_(O) is read out from the nonvolatilememory 14. In Step 212, P_(O) is substituted for Pd. The value stored inthe nonvolatile memory 14 at the origin detection operation of the focuslens 4 during the process adjustment is “0”. Therefore, in this example,Pd=0.

In Step 214, the motor 9 is shifted by one step at one time to theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter one by one). More specifically,in response to an instruction from the system control unit 13, theexciting position counter 151 is down-counted via the tracking positioncontrol unit 152. In accordance with this down-counting, the focus motordriving unit 11 rotates the motor 9 so as to shift the focus lens 4toward the imaging device 5.

In Step 215, a judgment is made as to whether the present excitingposition equals Pd (in this example, Pd=0) or not. In the case of notbeing equal, the process returns to Step 214 to make the motor 9 conductthe next one step operation. In the case of being equal, the processgoes to the next Step 216. In the example of FIG. 23, the positionsindicated by the judgment (n−2), the judgment (n−1) and the judgment (n)equal Pd (Pd=0) in the exciting position. In Step 216, a judgment ismade as to whether the photosensor output level exceeds the secondthreshold value or not at each of these positions.

Firstly, at the position of the judgment (n−2), a judgment is made as towhether the photosensor output level exceeds the second threshold valueor not. In the example of FIG. 23, it does not exceed the secondthreshold value, and therefore the process returns to Step 214 to makethe motor 9 conduct the next one step operation. After the repetition ofone step operation, at the position of the judgment (n−1), a judgment ismade again as to whether the photosensor output level exceeds the secondthreshold value or not. In the example of FIG. 23, it does not exceedthe second threshold value, and therefore the process returns to Step214 to make the focus motor conduct the next one step operation. Afterthe repetition of one step operation, at the position of the judgment(n), a judgment is made again as to whether the photosensor output levelexceeds the second threshold value or not. In the example of FIG. 23, itexceeds the second threshold value. In this case, the process goes toStep 207, where the absolute position counter 153 is preset at 0 (asshown in FIG. 23, the value of the absolute position counter surroundedwith the circle ◯).

Herein, the photosensor output level indicated by P2 in FIG. 23 shows alevel variation under the conditions of the mechanism and electricalproperties at the same operational environmental temperature andhumidity as those during the process adjustment. However, during thenormal operation in which the power may be turned on repeatedly, thephotosensor output level generates a variation different from P2 in therespective exciting positions of the motor 9 as indicated by P1 and P3.This results from errors in looseness in the lens unit driving directionand variations in mechanism and electrical properties due to atemperature and humidity change in the operation environment.

In the present embodiment, in the origin detection operation during thenormal operation, a judgment is made as to whether the photosensoroutput level exceeds a second threshold value or not at the judgment(n−2), the judgment (n−1) and the judgment (n) shown in FIG. 23, asdescribed above. The threshold value used in this case is not the firstthreshold value during the process adjustment but the second thresholdvalue.

Assuming that the threshold value is the first threshold value, if thephotosensor output level has the same level variation as in the processadjustment (P2 of FIG. 23), the origin can be reproduced accurately.However, when there is a variation in the level variation (P1, P3 ofFIG. 23) as described above, the origin detected also becomes varied.

According to the present embodiment, as described above, the secondthreshold value is a value of the photosensor output level where theexciting position of the motor 9 is at a half cycle of the excitation(electrical angle 180 degrees) earlier than the first threshold valueduring the process adjustment. Therefore, even if the photosensor outputlevel varies as in P1 and P3 as shown in FIG. 23, it is always judged toexceed the second threshold value at the judgment position of n.Similarly, it is always judged not to exceed the second threshold valueat the judgment positions of n−1 and n−2.

From this, even in the case where there is a variation within the rangefrom P1 to P3, the exciting position of the motor 9 always becomes “0”when the preset absolute position counter shows “0”, thus allowing theaccurate reproduction of the origin during process adjustment. That is,if it can be judged that the photosensor output level at a certainjudgment position does not exceed the second threshold value but thephotosensor output level at the next judgment position exceeds thesecond threshold value, the origin can be detected accurately.

Note here that a range of errors in looseness in the lens unit drivingdirection and variations in mechanism and electrical properties due to atemperature and humidity change in operation environment should bewithin the exciting position one cycle.

Also in the present embodiment, the focus position deviation due to theorigin detection position deviation can be prevented as described inEmbodiment 1 with reference to FIG. 7. That is, according to the presentinvention, the origin detection operation free from influences of errorsin looseness of the focus lens unit in the driving direction andvariations in mechanism and electrical properties due to a temperatureand humidity change in the operation environment can be realized.Therefore, the accuracy in absolute position of the focus lens unit canbe enhanced remarkably, and the present invention is especiallyeffective for a system performing a zooming operation while maintaininga focus condition.

Incidentally, in the present embodiment the difference between the firstthreshold value and the second threshold value is a differencecorresponding to a half cycle of the motor excitation cycle. However,the difference is not limited to this, and may be set within a rangefree from the influence of a variation in the photosensor output level.

For instance, the second threshold value may be set at a value within arange of the photosensor output level that is between the excitingposition corresponding to the origin and the exciting position that isone-cycle of the motor excitation cycle away from the exciting positioncorresponding to the origin.

Although the second threshold value may be set in advance prior to theprocess adjustment, this value may be set during the process adjustment.For instance, at the origin detection operation during the processadjustment, the system control unit 13 may store the photosensor outputlevel for each step of the motor 9, and the nonvolatile memory 14 maystore so that when the photosensor output level reaches the firstthreshold value, the photosensor output level of 4 steps earlier is setas the second threshold value. Thereby, a variation in the properties ofthe photosensor can be corrected, and an accurate threshold value can bedetermined.

Embodiment 8

The following describes Embodiment 8 of the present invention.Embodiment 8 is the same as in the configuration shown in FIG. 1 andFIG. 2 and the origin detection operation during the process adjustmentdescribed referring to FIG. 21 and FIG. 22.

Referring now to FIGS. 25 and 26, the origin detection operation of afocus lens 4 during the normal operation in Embodiment 8 is describedbelow. FIG. 25 is a drawing for explaining the origin detectionoperation during the normal operation according to Embodiment 8. Sincethe exciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.25 are the same as those described in FIG. 3, the duplicate explanationsare omitted.

Embodiment 8 is different from Embodiment 7 in that the excitingposition is decreased by two at one time when the focus lens 4 isshifted to the imaging device 5 side. Therefore, the counter value of anabsolute position counter 153, which operates in synchronization withthe exciting position, also is decreased by two at one time. Herein, theabsolute position counter sets a bit width so that the same value is notassigned to different positions in the movement range of the focus lens4.

In Embodiment 7, the time for one cycle of the driving signal is thetime T for both of the process adjustment and the normal operation asshown in FIGS. 21 and 23. However, in Embodiment 8, the time for onecycle of the driving signal during the normal operation is T/2 as shownin FIG. 25. Thereby, Embodiment 8 enables the origin detection operationduring the normal operation at twice the speed of Embodiment 7.

FIG. 26 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 8, which shows an operationflow described as a program in the system control unit 13. When thepower is turned on, the process starts with “origin detection start”. InStep 311, P_(O) is read out from the nonvolatile memory 14. In Step 312,P_(O) is substituted for Pd. Also in Embodiment 8, the example where thevalue stored in the nonvolatile memory 14 is “0” is described likeEmbodiment 1. Therefore, also in this example, Pd=0.

In Step 314, the motor 9 is shifted by two steps at one time in theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter by two at one time). Herein,the exciting position is set so as to include the above-obtained Pd (inthis case, Pd=0).

More specifically, in response to an instruction from the system controlunit 13, the exciting position counter 151 is down-counted via thetracking position control unit 152. In accordance with thisdown-counting, the focus motor driving unit 11 rotates the motor 9 so asto shift the focus lens 4 toward the imaging device 5.

In Step 315, a judgment is made as to whether the present excitingposition equals Pd (in this example, Pd=0) or not. In the case of notbeing equal, the process returns to Step 314 to make the motor 9 conductthe next two-step operation. In the case of being equal, the processgoes to the next Step 316.

The judgment positions are the positions indicated by the judgment(n−3), the judgment (n−2), the judgment (n−1) and the judgment (n) ofFIG. 25. In Step 316, a judgment is made as to whether the photosensoroutput level exceeds a second threshold value or not. In the case of notexceeding, the process returns to Step 314 to make the motor 9 conductthe next two-step operation. In the case of exceeding, the process goesto Step 317. At the time of exceeding, the absolute position counter 153is preset at 0 (as shown in FIG. 25, the value of the absolute positioncounter surrounded with the circle ◯).

The operation during these Steps 314 to 317 is the same as the operationduring Steps 214 to 217 described in the above Embodiment 7 withreference to FIG. 24. Further, even in the case where there is avariation of the photosensor output level within the range from P1 toP3, the origin during the process adjustment can be reproduced withreliability, which is similar to Embodiment 7. In addition, Embodiment 8enables the origin detection operation during the normal operation attwice the speed of Embodiment 7.

Incidentally, similarly to Embodiment 7, a range of errors in loosenessof the lens unit in the driving direction and variations in mechanismand electrical properties due to a temperature and humidity change inthe operation environment should be within the exciting position onecycle.

Embodiment 9

The following describes Embodiment 9 of the present invention.Embodiment 9 is the same as in the configuration shown in FIG. 1 andFIG. 2 and the origin detection operation during the process adjustmentdescribed referring to FIG. 21 and FIG. 22.

Referring now to FIGS. 27 and 28, the origin detection operation of afocus lens 4 during the normal operation in Embodiment 9 is describedbelow. FIG. 27 is a drawing for explaining the origin detectionoperation during the normal operation according to Embodiment 9. Sincethe exciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.27 are the same as those described in FIG. 21, the explanations for theduplication are omitted.

FIG. 28 is a flowchart of a power-off process according to Embodiment 9,which shows an operation flow described as a program in the systemcontrol unit 13. This drawing shows an example where when a power of amain body of an imaging device such as a still camera or a video movieis turned off by a main body switch (not illustrated), a transitionprocess to the power-off is performed.

When the power is turned off, the system control unit 13 starts theprocess with “power-off process start”. In Step 411, the motor 9 isshifted to the origin detection direction (the direction of the imagingdevice 5) by two steps at one time (decreases the exciting positioncounter by two at one time). Herein, the exciting position is set so asto include Pd (in this case, Pd =0) described in Embodiment 8. Morespecifically, in response to an instruction from the system control unit13, the exciting position counter 151 is down-counted via the trackingposition control unit 152. In accordance with this down-counting, thefocus motor driving unit 11 rotates the motor 9 so as to shift the focuslens 4 toward the imaging device 5.

In Step 412, if the counter value of the absolute position counter 153does not agree with the exciting position one cycle, the process returnsto Step 411 to make the focus motor conduct the next 2-step operation.In the case where they agree, the process goes to Step 413, where thepower of the main body is turned off. In this case, since the (excitingposition one cycle)=8, the power of the main body is turned off when(absolute position counter value)=8 (see FIG. 27).

Next, when the power is turned on by the main body switch, the operationis as follows: as described in Embodiment 8 with reference to FIG. 26,the process is conducted in accordance with the flowchart that startswith “origin detection start” when the power is turned on. Although thedescription of the midstream of the process is omitted to avoidduplication, in Step 316 of FIG. 26, a judgment is made as to whetherthe photosensor output level exceeds a second threshold value or not,and the counter value of the absolute position counter 153 is preset at“0” (as shown in FIG. 27, the value of the absolute position countersurrounded with the circle ◯).

As shown in FIG. 27, in the power-off transition process, the focusmotor is stopped immediately before the origin (immediately before thephotosensor output level exceeds a threshold value). Therefore, inEmbodiment 9, the first once judgment concerning the photosensor outputlevel is all that required to detect the origin when the power is tunedon. More specifically, since the position where the counter value of theabsolute position counter becomes “0” is the origin, the stoppingposition where the counter value agrees with the exciting position onecycle is the judgment position on the preceding side by one relative tothe final judgment position (origin). That is, the feature of thepresent embodiment resides in that the stopping position of the motor 9during the power-off transition process is a judgment positionimmediately preceding the position for the final judgment of thephotosensor output level when the power is turned on next.

The thus performed power-off transition process enables secure origindetection simply by the first once judgment of the photosensor outputlevel even when errors in looseness of the lens unit in the drivingdirection and variations in mechanism and electrical properties due to atemperature and humidity change in operation environment occur beforethe power is turned on next.

Incidentally, similarly to Embodiments 7 and 8, a range of errors inlooseness of the lens unit in the driving direction and variations inmechanism and electrical properties due to a temperature and humiditychange in operation environment should be within the exciting positionone cycle.

Embodiment 10

The following describes Embodiment 10 of the present invention.Embodiment 10 is the same as in the configuration shown in FIG. 1 andFIG. 2. Referring now to FIGS. 29 and 30, the origin detection operationof a focus lens 4 during the normal operation in Embodiment 10 isdescribed below.

FIG. 29 is a drawing for explaining the origin detection operationduring the process adjustment according to Embodiment 10. Since theexciting position, the A-phase current, the B-phase current, theabsolute position counter and the photosensor output level shown in FIG.29 are the same as those described in FIG. 21 of Embodiment 7, theduplicate explanations are omitted. Further, this embodiment is the sameas Embodiment 7 in that the exciting position is decreased one by onealong with the movement of the focus lens 4 to the imaging device 5side.

FIG. 30 is a flowchart of an origin detection operation during theprocess adjustment according to Embodiment 10, which shows an operationflow described as a program in the system control unit 13. This processstarts with “origin adjustment start” when the power is turned on. InStep 511, on a liquid crystal display (not illustrated) showing aprocess adjustment menu, for example, “main body upward” is displayed. Alens 2 of the imaging apparatus is turned upward, and the process goesto the next Step 512.

In Step 512, the motor 9 is shifted to the origin detection direction(the direction of the imaging device 5) by one step at one time(decreases the exciting position counter one by one). More specifically,in response to an instruction from the system control unit 13, theexciting position counter 151 is down-counted via the tracking positioncontrol unit 152. In accordance with this down-counting, the focus motordriving unit 11 rotates the motor 9 so as to shift the focus lens 4toward the imaging device 5.

In Step 513, a judgment is made as to whether the photosensor outputlevel exceeds a first threshold value or not. In the case of notexceeding, the process returns to Step 512 to make the motor 9 conductthe next one step operation. In the case of exceeding, the process goesto Step 514, where the exciting position at the time of exceeding issubstituted as Pu. In this case, the exciting position “2” issubstituted for Pu.

Next, in Step 515, on the liquid crystal display (not illustrated)showing a process adjustment menu, for example, “main body downward” isdisplayed. The lens 2 of the imaging apparatus is turned downward, andthe process goes to the next Step 516. In Step 516, the motor 9 isshifted to the origin detection direction (the direction of the imagingdevice 5) by one step at one time (decreases the exciting positioncounter one by one).

Note here that the reason for generating a step in the photosensoroutput level when the attitude is changed from “upward state” to“downward state” in FIG. 29 is that the focus lens 4 is shifted to thedirection moving away from the imaging device 5 because of its ownweight and looseness (e.g., looseness of the rack for transferring thefocus lens 4 with the lead screw of the motor 9).

In Step 517, a judgment is made as to whether the photosensor outputlevel exceeds the first threshold value or not. In the case of notexceeding, the process returns to Step 516 to make the motor 9 conductthe next one step operation. In the case of exceeding, the process goesto Step 518, where the exciting position at the time of exceeding issubstituted as Pd.

In this case, the exciting position “6” is substituted as Pd. In Step519, the magnitude of Pd and Pu is judged. In this case, since Pu=2 andPd=6, the process goes to the next Step 519 a. In Step 519 a,Pd=Pd−(exciting position one cycle) is calculated, and since (excitingposition one cycle)=8, Pd=−2 is determined. When, using this value ofPd, P is determined by the formula of Step 520, P=INT((2−2)/2)=0 isobtained. Incidentally, INT means to round down the figures from thedecimal fractions. In this example, since it is not the case of P<0 inStep 521, the process goes to the next Step 522 and P=0 is stored asP_(O) in the nonvolatile memory.

In Step 523, the counter value of the absolute position counter 153 ispreset at −INT ((Pu—Pd)/2). The value of −INT ((Pu—Pd)/2) becomes −INT((2+2)/2)=−2. With this calculation, it can be calculated how far apartin exciting position the origin at the time of downward and the originof the intermediate are between the times of upward and downward. Asshown in FIG. 29, assuming that the numerical value of the absoluteposition counter at the origin at the time of downward is −2 as thecalculated value (the value surrounded with the circle ◯), the countervalue of the absolute position counter 153 at the origin (excitingposition “0”) of the intermediate between at the time of upward anddownward becomes “0”.

In the case of P<0 in Step 521, there is no corresponding numericalvalue for the exciting position. However, the calculation in Step 521 aallows the exciting position corresponding to P in Step 520 to bedetermined.

In the afore-mentioned example, the example of Pd>Pu is described inStep 519. On the contrary, in the case of Pd≦Pu, the process may go toStep 520 directly. In the case of Pd≦Pu, the intermediate positionbetween Pu and Pd can be determined from the calculation of Step 520without the need of correction of the value of Pd in Step 519 a.

In this way, according to Embodiment 10, the origin stored in thenonvolatile memory 14 is the intermediate position of the originsdetected in the upward state and the downward state. Therefore ascompared with the case where the origin is adjusted withoutconsideration given to the difference due to attitude as described inEmbodiment 1, which might cause an upward attitude difference during theadjustment and cause a downward attitude difference during the normaloperation, for example, Embodiment 10 allows an error in lens positiondue to attitude difference to be improved to ½.

Further, in Embodiment 10, the example where the origin is detected inthe upward state firstly, and then the origin is detected in thedownward state is described. However, if, considering looseness, theposition in the upward state is farther away from the origin than in thedownward state, the origin may be detected in the downward statefirstly, followed by the origin detection in the upward state.

Further, in an imaging apparatus in which a variation in origindetection position due to attitude difference is specified as aspecification, the origin may be detected in either the upward state orthe downward state, and the position deviated from the detected positionby half of the specification may be set as the origin, whereby the sameeffects can be obtained.

The present embodiment is on the precondition that there is a variationin origin detection position due to attitude difference of a lensbarrel. However, if the accuracy of a lens barrel can be secured so thata variation in origin detection position due to attitude difference of alens barrel can be ignored, the configuration of the above-statedEmbodiments 7 to 9 may be adopted.

Embodiment 11

The following describes Embodiment 11 of the present invention. Adriving apparatus according to Embodiment 11 includes a temperaturesensor and an angular sensor, which have the configuration shown inFIGS. 16 and 17.

Referring now to FIGS. 31 and 32, an origin detection operation of thefocus lens 4 during the normal operation in Embodiment 11 will bedescribed below. FIG. 31 is a drawing for explaining an origin detectionoperation during the normal operation according to Embodiment 11. FIG.31(a) is intended to show the state where the temperature is higher thana room temperature and the lens 2 of the lens barrel 1 faces upward, andFIG. 31(b) is intended to show the state where the temperature is lowerthan a room temperature and the lens 2 of the lens barrel 1 facesdownward.

Since the exciting position, the A-phase current, the B-phase current,the absolute position counter and the photosensor output level shown inFIG. 31 are the same as those described in FIG. 21 of Embodiment 7, theduplicate explanation are omitted. Further, the exciting position isdecreased by two at one time along with the movement of the focus lens 4to the imaging device 5 side, which is similar to the example of FIG. 25of Embodiment 8.

FIG. 32 is a flowchart of the origin detection operation during thenormal operation according to Embodiment 11, which shows an operationflow described as a program in the system control unit 13. When thepower is turned on, the process starts with “origin detection start”. InStep 611, P_(O) is read out from the nonvolatile memory 14. In Step 612a, Pd=P_(O). The value stored in the nonvolatile memory 14 at the origindetection operation of the focus lens 4 during the process adjustment is“0”, which is similar to Embodiment 7. Therefore, in this example, Pd=0.

In Step 612 b, in accordance with information output from thetemperature sensor 16 and the angular sensor 17, a correction value ΔPdis added to Pd. In the case where the lens 2 of the lens barrel 1 facesupward, the focus lens 4 moves closer to the imaging device 5 ascompared with the horizontal position due to its own weight andlooseness (e.g., looseness of the rack for transferring the focus lens 4with the lead screw of the motor 9). Moreover, in the case where thetemperature is higher than a room temperature and the photo-interruptionmember 7 has a thermal expansion coefficient larger than those of thelens barrel 1 and the motor 9, the photo-interruption member 7 movescloser to the photosensor 8.

For those reasons, as shown with P4 of the photosensor output level ofFIG. 31(a), the timing when the photosensor output level changes at thetime of the origin detection becomes earlier than the photosensor outputlevel P2 that shows the case where the lens is in a horizontal positionat a room temperature. In this case, an example where an error occurringdue to the temperature increase from a room temperature corresponds toone step of the exciting position of the motor 9 and an error occurringwhen the imaging apparatus in a horizontal position is made to faceupward corresponds to one step of the exciting position of the motor 9,whereby an error corresponding to two steps in total occurs, is shown.

Therefore, since ΔPd=2, Pd2=2 is calculated in Step 602 b. In Step 613,a judgment is made as to whether Pd2 is negative or not. In the casewhere Pd2 is 0 or positive, the process goes to the next Step 614. Inthe case where Pd2 is negative, Pd2=Pd2+(exciting position one cycle) iscalculated in Step 613 a, and then the process goes to the next Step614. The reason for undergoing Step 613 a in the case of Pd2 beingnegative is the same as the reason for undergoing Step 521 a of FIG. 30in Embodiment 10.

In Step 614, the motor 9 is shifted by two steps at one time to theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter by two at one time). Herein,the exciting position is set so as to include the above-obtained Pd2 (inthis case, Pd2=2). More specifically, in response to an instruction fromthe system control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 615, a judgment is made as to whether the present excitingposition equals Pd2 (in this example, Pd2=2) or not. In the case of notbeing equal, the process returns to Step 612 b to make the motor 9conduct the next two-step operation. In the case of being equal, theprocess goes to the next step 616.

The positions with Pd2=2 are positions indicated with the judgment(n−2), the judgment (n−1) and the judgment (n) shown in FIG. 31(a).Since the exciting position is 2 at these judgment positions, this isthe position advancing by two steps from the exciting position 0 thatshows a position before adding the correction value (i.e., a positionmoving away from the imaging device 5). Therefore, the judgment at thesejudgment positions can be substantially equal to the case where thephotosensor output level P2 for the lens in a horizontal position at aroom temperature is detected at a position where the exciting positionis 0.

In Step 616, a judgment is made as to whether the photosensor outputlevel exceeds a second threshold value or not at the above-statedjudgment positions. In the case of not exceeding, the process returns toStep 612 b to make the focus motor conduct the next two-step operation.In the case of exceeding, the process goes to Step 617. At the time ofexceeding, the absolute position counter 153 is preset at ΔPd. Herein,this is preset at “2” because ΔPd=2 (as shown in FIG. 31(a), the valueof the absolute position counter surrounded with the circle ◯).

Note here that the explanations for FIG. 26 of Embodiment 8 show theexample where if the conditions are not satisfied in Step 315 or Step316, the process returns to Step 314. On the contrary, Embodiment 11shows the example where the process returns to Step 612 b. This isbecause according to Embodiment 11 in the case where a temperaturechanges or the attitude difference changes during the origin detectionoperation, a position for judging whether the photosensor output levelexceeds a threshold value or not is changed successively.

The following describes the case where the lens 2 of the lens barrel 1faces downward and the temperature is lower than a room temperature,with reference to FIG. 31(b) and FIG. 32. In the case where the lens 2of the lens barrel 1 faces downward, the focus lens 4 moves away fromthe imaging device 5 as compared with the horizontal position due to itsown weight and looseness (e.g., looseness of the rack for transferringthe focus lens 4 with the lead screw of the motor 9). Moreover, in thecase where the temperature is lower than a room temperature and thephoto-interruption member 7 has a thermal expansion coefficient largerthan those of the lens barrel 1 and the motor 9, the photo-interruptionmember 7 moves away from the photosensor 8.

For those reasons, as shown with P5 of the photosensor output level ofFIG. 31(b), the timing when the photosensor output level changes at thetime of the origin detection becomes later than the photosensor outputlevel P2 that shows the case where the lens is in a horizontal positionat a room temperature. In this case, an example where an error occurringdue to the temperature decrease from a room temperature corresponds toone step of the exciting position of the motor 9 and an error occurringwhen the imaging apparatus in a horizontal position is made to facedownward corresponds to one step of the exciting position of the motor9, whereby an error corresponding to two steps in total occurs, isshown.

Therefore, since ΔPd=−2, Pd2=−2 is calculated in Step 612 b. In Step613, a judgment is made as to whether Pd2 is negative or not. In thecase where Pd2 is negative, Pd2=Pd2+(exciting position one cycle) iscalculated in Step 613 a, and then the process goes to the next step. Inthe case where Pd2 is 0 or positive, the process goes to the next step.In this case, the resultant Pd2 is 6, because −2+8=6.

In Step 614, the motor 9 is shifted by two steps at one time to theorigin detection direction (the direction of the imaging device 5)(decreases the exciting position counter by two at one time). Herein,the exciting position is set so as to include the above-obtained Pd2 (inthis case, Pd2=6). More specifically, in response to an instruction fromthe system control unit 13, the exciting position counter 151 isdown-counted via the tracking position control unit 152. In accordancewith this down-counting, the focus motor driving unit 11 rotates themotor 9 so as to shift the focus lens 4 toward the imaging device 5.

In Step 615, a judgment is made as to whether the present excitingposition equals Pd2 (in this example, Pd2=6) or not. In the case of notbeing equal, the process returns to Step 612 b to make the motor 9conduct the next two-step operation. In the case of being equal, theprocess goes to the next Step 616. The positions with Pd2=6 arepositions indicated with the judgment (n−3), the judgment (n−2) and thejudgment (n−1) shown in FIG. 31(b). Since the exciting position is 6 atthese judgment positions, this is the position behind by two steps fromthe exciting position 0 that shows a position before adding thecorrection value (i.e., a position moving closer to the imaging device5). Therefore, the judgment at these judgment positions can besubstantially equal to the case where the photosensor output level P2for the lens in a horizontal position at a room temperature is detectedat a position where the exciting position is 0.

In Step 616, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not at the above-stated judgmentpositions. In the case of not exceeding, the process returns to Step 612b to make the focus motor conduct the next two-step operation. In thecase of exceeding, the process goes to Step 617. At the time ofexceeding, the absolute position counter 153 is preset at ΔPd.

Herein, this is preset at “−2” because ΔPd=−2 (as shown in FIG. 31(b),the value of the absolute position counter surrounded with the circle◯). Note here that the explanations for FIG. 26 of Embodiment 8 show theexample where if the conditions are not satisfied in Step 315 or Step316, the process returns to Step 314. On the contrary, Embodiment 11shows the example where the process returns to Step 612 b. This isbecause in the case where a temperature changes or the attitudedifference changes during the origin detection operation, a position forjudging whether the photosensor output level exceeds a threshold valueor not is changed successively.

The photosensor output level indicated by “P2” in FIG. 31 shows a levelvariation under the conditions of the mechanism and electricalproperties at the same operational environmental temperature andhumidity as those during the process adjustment. However, during thenormal operation in which the power may be turned on repeatedly, avariation occurs in the position of a level change in accordance withthe exciting positions of the motor 9, as indicated by “P4” and “P5”.This results from errors in looseness in the lens unit driving directionand variations in mechanism and electrical properties due to atemperature change in the operation environment.

In Embodiment 11, however, in the origin detection operation during thenormal operation, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not at the respective judgmentpositions shown in FIG. 31. Therefore, even when a variation occurswithin the range from “P4” to “P5”, the exciting position of the motor 9always becomes “0” when the counter value of the absolute counter 153 is“0”, thus allowing the origin during the process adjustment to bereproduced as described in Embodiment 7.

The above-description shows the example using the temperature sensor andthe angular sensor. However, the use of a humidity sensor also enablesthe improvement of accuracy by improving an error occurring due to adifference in hygroscopic coefficient of the lens barrel and the lens.Further, Embodiment 11 allows the origin detection operation during thenormal operation conducted at twice the speed of Embodiment 7.

Further, if errors in looseness in the lens unit driving direction andvariations in mechanism and electrical properties due to a temperatureand humidity change in the operation environment can be detected using atemperature sensor and an angular sensor, the correction is possibleeven when these errors exceed the range of the exciting position onecycle.

Note here that the explanations of the zooming operation in the aboveEmbodiment 6 referring to FIG. 20 are true for the present embodiment.

Embodiment 11 explains the example with consideration given to the casewhere angles and temperatures of the lens barrel differ between theprocess adjustment and the normal operation. However, theseconfigurations are not always the optimum one. For instance, in the casewhere a variation in photosensor output level due to changes in angleand temperature is suppressed by the configuration of the lens barrel orthe like, the configurations of Embodiments 7 to 9 are suitable.

Although Embodiment 11 explains the example of having both of theangular sensor and the temperature sensor, the configuration having oneof these sensors also is possible. For instance, in the case where avariation in a changing position of the photosensor output level due toa temperature change does not pose a problem especially, the correctioncan be conducted using an angular sensor only.

Further, although Embodiment 11 shows the example where the ΔPd is addedin Step 612 b of FIG. 32, ΔPd may be subtracted.

In the above-stated Embodiments 8, 9 and 11, the example where at thetime of the origin detection operation during the normal operation thelens unit is driven at twice the speed of the process adjustment isshown. However, these examples are non-limiting, and the operation atfour times or more the speed also is possible. That is, in the casewhere a time of the driving signal one cycle is T during the processadjustment, a time of the driving signal one cycle during the normaloperation may be T/N (N denotes an integer of 2 or more), and a drivingsignal with 1/N cycle may be output.

Further, in Embodiments 9 and 11, the driving signal one cycle may bethe same for the process adjustment and the normal operation.

Further, although the exciting positions obtained by dividing the cycleof the driving signal of the motor into 8 sections are described above,these embodiments are not limited in the division number. For example,division into 4 and 16 sections may be set depending on the requiredaccuracy.

Further, the above-described embodiments explain the example using astepping motor as the driver. However, this may be other motors as longas an exciting signal of the motor has periodicity, and a linear motorfor example may be used.

Embodiment 12

The following describes Embodiment 12 of the present invention, withreference to the drawings. FIG. 33 includes a schematic diagram and ablock diagram of an imaging apparatus according to Embodiment 12. InFIG. 33, numeral 1 denotes a lens barrel and 19 denotes a camera mainbody. The lens barrel 1 includes imaging lens groups, in which a fixedlens group 2 as a first lens group, a fixed lens group 3 as a secondlens group and a focus lens 4 as a third lens group are arranged in thisorder from the side of a subject. The fixed lens groups 2 and 3 arefixed to the lens barrel 1. A motor 9 as a focus motor and a motordriving unit 11 make up a motor driver. Along with the rotation of themotor 9, the focus lens 4 moves in the optical axis direction along alead screw with threads cut therein so as to enable the adjustment offocus.

In the example of FIG. 33, the motor 9 is a stepping motor that rotatesin accordance with a phase of a driving signal (exciting signal) for amotor coil output from a focus motor driving unit 11. Numeral 5 denotesan imaging device that converts an image of a subject captured throughthe fixed lens groups 2 and 3 and the focus lens 4 into an electricsignal. Numeral 7 denotes a photo-interruption member that is fixed to aframe of the focus lens 4.

As illustrated by the dotted lines of FIG. 33, the focus lens 4 isshifted in the direction of the imaging device 5 so as to interrupt aphotosensor 8 as a position detection sensor by the photo-interruptionmember 7, whereby the origin of the focus lens 4 is detected.

Numeral 12 denotes a signal processing unit that generates image dataand contrast information for performing focus adjustment based on anelectric signal output from the imaging device 5. Numeral 17 denotes adata transmission/reception unit provided in the lens barrel 1, and 18denotes a data transmission/reception unit provided in the camera mainbody 19. Numeral 15 denotes a motor control unit as a motor controllerfor the motor 9. A user is allowed to perform focus adjustment based onthe image processed by the signal processing unit 12. Further, automaticfocus adjustment (auto-focus function) can be performed as well based onthe contrast information of the signal processing unit 12 so that thecontrast is maximized. In either case, the motor control unit 15 outputsan instruction to the motor control unit 11 via the datatransmission/reception units 17 and 18 so as to drive the focus lens 4.

Numeral 14 denotes a nonvolatile memory as a storage, and 16 denotes apower supply. A voltage to be applied to the motor driving unit 11 isset in accordance with the information concerning a motor applicationvoltage stored in the nonvolatile memory 14. This will be describedlater in detail. Numeral 20 denotes a temperature sensor and 21 denotesan angular sensor whose output varies with the attitude angle of thecamera main body 19. Outputs from these sensors are input to the motorcontrol unit 15, which are used to correct the position of the focuslens 4.

FIG. 34 is a detailed block diagram of the focus motor control unit 15shown in FIG. 33. In FIG. 34, the focus motor control unit 15 includes acontrol unit 13, an exciting position counter 151 and an absoluteposition counter 153. The exciting position counter 151, based on afocus moving direction and moving step information output from thecontrol unit 13, counts up or counts down the exciting position counterfor controlling a phase of a driving signal for the motor 9 and forcontrolling the position of the focus lens 4.

In the above configuration of FIG. 33, the position of the focus lens 4is controlled by the rotation of the motor 9. The rotation of the motor9 is controlled by a periodic driving signal from the motor driving unit11 that receives a signal from the motor control unit 15 via the datatransmission/reception units 18 and 17.

Immediately after the power is turned on, the control unit 13 reads outinformation concerning lens control that is stored in the nonvolatilememory 14 provided in the lens barrel 1 and then performs a focus origindetection process, which will be described later in detail. In the focusorigin detection process, firstly, the focus lens 4 is driven toward theimaging device 5. As the focus lens 4 is driven in this way, thephotosensor 8 is interrupted by the photo-interruption member 7. Inaccordance with this interruption amount, a signal level of thephotosensor 8 varies, and when the signal level exceeds a thresholdlevel (or falls below a threshold value in some circuit configurations)under predetermined conditions, the absolute position counter 153 isreset or preset.

After the completion of this process, the motor control unit 15transmits control information for the motor 9 to the motor driving unit11 via the data transmission/reception units 18 and 17. When receivingthis control information, the motor driving unit 11 outputs a drivingsignal having periodicity based on the received signal so as to controlthe position of the focus lens 4. As shown in FIG. 34, the informationtransmitted from the motor control unit 15 includes informationtransmitted via the exciting position counter 151 and informationdirectly transmitted from the control unit 13 to the datatransmission/reception unit 18.

The information transmitted via the exciting position counter 151relates to the position of the focus lens 4. In accordance with thecontrast information from the signal processing unit 12, the rotationalposition information of the motor 9 output from the exciting positioncounter 151 and the positional information of the focus lens 4 outputfrom the absolute position counter 153, the control unit 13 outputs themoving direction and the moving step information of the motor 9 to theexciting position counter 151 so as to control the position of the focuslens 4. The information directly transmitted from the control unit 13 tothe data transmission/reception unit 18 includes information relating toan application voltage and the maximum driving rate of the motor 9, forexample.

Herein, the absolute position counter 153 operates in synchronizationwith a counter value of the exciting position counter 151. The excitingposition counter 151 comes full circle to correspond to one cycle (360degrees) of a driving electrical angle of the motor 9, whereas theabsolute position counter 153 shows the absolute position with referenceto a value reset under a predetermined condition.

The transmission/reception of information between the lens barrel 1 andthe camera main body 19 is conducted between the datatransmission/reception units 17 and 18. When detaching the lens barrel 1from the camera main body 19, the detaching can be conducted at ajunction part (not illustrated) of the data transmission/reception units17 and 18 and a junction part (not illustrated) of the motor drivingunit 11 and the power supply 16.

In the present embodiment, the motor control unit 15 for controlling thefocus lens 4 is not disposed in the lens barrel 1 or to be sharedbetween the lens barrel 1 and the camera main body 19, but is disposedin the camera main body 19. Therefore, the processing of the informationstored in the nonvolatile memory 14 is carried out not in the lensbarrel 1 but by the motor control unit 15 in the camera main body 19.That is, the information in the nonvolatile memory 14 is transmitted tothe motor control unit 15 via the data transmission/reception units 17and 18, is processed in the camera main body 19 and is transmitted againto the lens barrel 1. With this configuration, there is no need toprovide a large scale microcomputer for controlling in the lens barrel1, thus making the lens barrel 1 compact and reducing a cost. Althoughthe lens barrel 1 is provided with the data transmission/reception unit17, this is intended mainly to exchange data between the lens barrel 1and the camera main body 19, so that a simple configuration can sufficefor this purpose.

FIG. 35 is a drawing for explaining the operation of the datatransmission/reception units 17 and 18. “CK” represents a clock fordetecting “DATA” (in this case, address, data 1, data 2 and parity).This “CK” is transmitted from the data transmission/reception unit 18 ofthe camera main body 19 to the data transmission/reception unit 17 ofthe lens barrel 1. The data transmission/reception unit 17 reads outdata corresponding to the respective addresses from the nonvolatilememory 14.

“DE” also is output from the data transmission/reception unit 18 of thecamera main body 19 to the data transmission/reception unit 17 on thelens barrel 1 side. The data transmission/reception unit 17 recognizesan address 8-bit data immediately after “DE” changes from “H” level to“L” level. Next, the data transmission/reception unit 17 recognizes8-bit data after the address during the “L” level period as data (inthis case, as data 1 and data 2).

Herein, 16-bit data is transmitted/received so that data 1 is ahigh-order 8 bit and data 2 is a low-order 8 bit. 24-bit data istransmitted/received so that data 1 is a high-order 8 bit, data 2 is amiddle-order 8 bit and data 3 is a low-order 8 bit.

Next, 8-bit data immediately after the change from “L” level to “H”level is made parity. The parity is a value obtained by the calculationof (address)XOR(data1)XOR(data2), and this calculation is performed bythe data transmission/reception unit 17 and the calculated value istransmitted to the data transmission/reception unit 18. The motorcontrol unit 15 receives data from the data transmission/reception unit18, and calculates (address)XOR(data1)XOR(data2) like the datatransmission/reception unit 17. If the calculated value does not agreewith the received parity, the motor control unit 15 transmits orreceives data again.

The following Table 1 shows information (hereinafter called “memory READinformation”) that is read out only during the normal operation of theimaging apparatus, which is included in information stored in thenonvolatile memory 14. The memory READ information is written in thenonvolatile memory 14 during the manufacturing process. TABLE 1 MemoryREAD information Address Data excitation method 0x00 0x02 maximumresponse frequency 0x01 0x0DAC maximum self-start frequency 0x03 0x02D0motor current 0x05 0x46 motor voltage 0x06 0x32 focus lens unit shiftamount 0x07 0x0F magnetic pole number 0x08 0x0A rotation resolution 0x090x08 focal distance 0x0A 0x0023 maximum operation cycle 0x0C 0x0186A0reference exciting position 0x0F 0x04 subject distance ∞ - focusposition 0x10 0x0198 subject distance 2 m - focus position 0x12 0x01BAsubject distance 1 m - focus position 0x14 0x01D9 subject distance 0.5m - focus position 0x16 0x0213 focus position correction amount bytemperature 0x18 0x06 focus position correction amount by attitude angle0x19 0x1F . . . . . . . . .

As shown in Table 1, the information stored in the nonvolatile memory 14forms an information table in which data corresponds to a plurality ofaddresses. The same goes for the following Tables 2 and 3.

In Table 1, the data of “excitation method” at address 0x00 includesone-phase excitation (0x00), two-phase excitation (0x01), one-two phaseexcitation (0x02) and the like in the case of a stepping motor, andTable 1 shows the case of one-two phase excitation (0x02).

The “maximum response frequency” at address 0x01 relates to the maximumdriving rate of the motor. Table 1 exemplifies the case of one-two phaseexcitation, which shows 3500 [pps] obtained by converting data 0x0DACinto a decimal number. The “maximum self-start frequency” at 0x03 alsorelates to the maximum driving rate of the motor. Table 1 exemplifiesthe case of one-two phase excitation, which shows 720 [pps], 15 obtainedby converting data 0x2D0 into a decimal number.

The “motor current” at address 0x05 shows 70 [mA] obtained by convertingdata 0x46 into a decimal number. The “motor voltage” at address 0x06shows 50[×10⁻¹ V], obtained by converting data 0x32 into a decimalnumber. Based on this information of the motor voltage, the control unit13 makes the power supply 16 set an application voltage of the motordriving unit 11.

The focus lens unit shift amount at address 0x07 shows 15 [μm], obtainedby converting data 0x0F into a decimal number in the case of one-twophase excitation. The magnetic pole number at address 0x08 shows 10[poles], obtained by converting data 0x0A into a decimal number, and onecycle of the driving signal of the motor 9 corresponds to 72 [degrees]when it is converted into the rotational angle. As described below, therotation resolution per cycle of the driving signal of the motor 9 is 8[sections], and therefore when the above-stated focus lens unit shiftamount 15 [μm] is converted into the rotational angle of the motor 9, itcan be found that this corresponds to 72/8=9 [degrees].

The rotation resolution at address 0x09 shows 8 [sections], obtained byconverting data 0x08 into a decimal number, which is the rotationresolution per cycle of the driving signal of the motor 9, and when itis converted into the rotational angle of the motor 9, this correspondsto 72/8=9 [degrees] as stated above.

The focal distance at address 0x0A shows 35 [mm], obtained by convertingdata 0x0023 into a decimal number. The maximum operation cycle ataddress 0x0C shows 100,000 [cycles], obtained by converting data0x0186A0 into a decimal number, which shows the maximum operation cycleassuming the rotation of the motor 9 corresponding to the reciprocatingdistance within a movable range of the focus lens 4 as one [cycle], forexample. Although the reference exciting position at address 0x0F willbe described later in detail, this shows the reference exciting positionof the motor 9 that is performed during the process adjustment.

The subject distance ∞—focus position at address 0x10 shows the positionof the focus lens 4 with a value of the absolute position counter 153when the distance from the imaging device 5 to a subject is ∞. Similarlyto the case of the distance so to the subject, the data at address 0x12,address 0x14 and address 0x16 show the counter values of the absoluteposition counter 153 in the case of the distance between the imagingdevice 5 to the subject of 2 m, 1 m and 0.5 m, respectively.

The respective data show the values of the absolute position counter 153where the origin is 0. The value of the subject distance ∞—focusposition at address 0x10 is 408, obtained by converting 0x0198 into adecimal number. The value of the subject distance 2 m—focus position ataddress 0x12 is 442, obtained by converting 0x01BA into a decimalnumber. The value of the subject distance 1 m—focus position at address0x14 is 473, obtained by converting 0x01D9 into a decimal number. Thevalue of the subject distance 0.5 m—focus position at address 0x16 is531, obtained by converting 0x0213 into a decimal number.

In this way, the lens barrel 1 according to the present embodiment isprovided with data therein by which the relationship between therotational angle of the motor 9 and the subject distance is clarified.In the case where a plurality of types of lens barrels 1 are preparedfor interchangeable lenses, data corresponding to the above-stated datamay be stored in the non-volatile memory 14 of each lens barrel 1,whereby the focus lens position can be controlled precisely irrespectiveof the types of the lens barrels 1.

The focus position correction amount by temperature at address 0x18shows a correction amount for a change of 10° C., represented with thevalue of the absolute position counter 153, and this is 6 by convertingdata 0x06 into a decimal number. The focus position correction amount byattitude angle at address 0x19 shows a correction amount for a change of90°, represented with the value of the absolute position counter 153,and this is 31 by converting data 0x1F into a decimal number. Thesecorrections by temperature and attitude angle will be described later indetail.

The following Table 2 shows information (hereinafter called “memoryWRITE/READ information”) that is for performing reading out and writingoperations during the normal operation of the imaging apparatus, whichis included in information stored in the nonvolatile memory 14. The dataof the above Table 1 corresponding to the addresses are written duringthe manufacturing process and are read out during the normal operation,whereas data of Table 2 corresponding to addresses are both read out andwritten during the normal operation.

In the following, it is assumed that data is written in the nonvolatilememory 14 in the case where the highest bit of a 8-bit address is “1”,and data is read out from the nonvolatile memory 14 in the case wherethe highest bit of a 8-bit address is “0”, which will be described aswriting address/reading-out address, respectively. TABLE 2 MemoryWRITE/READ information Address Data operation cycle 0x90/0x10 0x000010 .. . . . . . . .

In Table 2, the operation cycle at address 0x90/0x10 shows the operationcycle, assuming the rotation of the motor 9 corresponding to thereciprocating distance within a movable range of the focus lens 4 as one[cycle], for example.

Assuming that the reference of this one cycle is the subject distance of0.5 m where the focus position is the farthest from the origin, thefocus position in this case has the reciprocating distance of531×2=1062, because the counter value is 531, i.e., the focus positionis at a position 531 away from the origin. Therefore, in the case wherethe count reaches 1062, +1 cycle may be added to the read out operationcycle, thus enabling the management of the operation cycle of the motor9.

In this case, the control unit 13 may manage the operation cycle so thatthe operation cycle is written in the nonvolatile memory 14 via the datatransmission/reception units 18 and 17 immediately before turning offthe power, whereby the operation cycle can be updated into the latestone.

The following Table 3 shows control information transmitted/receivedbetween the data transmission/reception units 17 and 18. TABLE 3 Controlinformation Address Data photosensor output level 0x20 0x00 motorexciting position 0xA0 0x04 . . . . . . . . .

In Table 3, the photosensor output level at address 0x20 is an outputlevel that changes as the focus lens 4 is driven toward the imagingdevice 5 so that the photosensor 8 is interrupted by thephoto-interruption member 7. When the signal level of the photosensor 8changes and exceeds a threshold value under predetermined conditions (orfalls below a threshold value in some circuit configurations), the datastored in the nonvolatile memory 14 changes from 0x00 to 0x01, forexample.

The motor exciting position at address 0xA0 shows the exciting positionof the motor 9, which can be represented with 8 values of 0x00, 0x01, .. . 0x07 when one cycle of the driving signal of the motor 9 is dividedinto 8 sections as one-two phase excitation. In this case, the excitingposition of 0x04 is shown, which is an output value of the excitingposition counter 151.

The following describes a lens initialization operation when the poweris turned on in the normal operation mode. FIG. 36 is a flowchart of thelens initialization operation. This flowchart shows the operation by aprocessing program in the control unit 13. In Step 121, internal memoryof the control unit 13 is cleared. In Step 122, memory READ informationstored in the nonvolatile memory 14 provided in the lens barrel 1 isreceived.

In Step 123, confirmation is conducted to compare the parity received asdescribed above with the parity calculated by the control unit 13,whereby a judgment is made as to whether these parities agree or not. Ifthey agree, the process goes to the next Step 124, and if they do notagree, the process goes to Step 123 a. In Step 123 a, 1 is added to avariable i (initial value is 0), and the process goes to Step 123 b, andin Step 123 b, a judgment is made as to whether the variable i is apredetermined number of times or more (e.g., 3) or not. In the casewhere the variable i is smaller than the predetermined number of times,the process returns to Step 122, and the similar operation is performed.In the case where the variable i reaches the predetermined number oftimes, the lens initialization is regarded as NG so as to complete thelens initialization operation.

In Step 124, memory WRITE/READ information stored in the nonvolatilememory 14 is received. In Step 125, confirmation is conducted to comparethe parity received as described-above with the parity calculated by thecontrol unit 13, whereby a judgment is made as to whether these paritiesagree or not. If they agree, the process goes to the next Step 126, andif they do not agree, the process goes to Step 125 a.

In Step 125 a, 1 is added to a variable k (initial value is 0), and theprocess goes to Step 125 b, and in Step 125 b, a judgment is made as towhether the variable k is a predetermined number of times or more (e.g.,3) or not. In the case where the variable is smaller than thepredetermined number of times, the process returns to Step 124, and thesimilar operation is performed. In the case where the variable k reachesthe predetermined number of times, the lens initialization is regardedas NG so as to complete the lens initialization operation. In Step 126,a focus origin detection process is performed, and the lensinitialization operation is completed.

After completion of the lens initialization operation, normal operationis conducted based on the memory READ information received from thenonvolatile memory 14, and after completion of the normal operation,memory WRITE/READ information is updated to new information.

Further, when the lens barrel 1 is replaced with a new lens barrel 1,the control unit 13 will receive information corresponding to the newlens barrel 1 by undergoing the above-described steps of FIG. 36.

Therefore, even when the lens barrel 1 is replaced with another one, theposition of the focus lens 4 can be controlled by the focus control unit15 of the camera main body 19 in accordance with the operationconditions of the motor 9 and the focus lens 4 provided in the replacedlens barrel 1. Although the information stored in the nonvolatile memory14 is as described referring to the above Tables 1 to 3, the followingsupplementary explanation is given referring to Tables 1 to 3.

By using the information of the magnetic pole number of the motor, therelationship of the rotational angle of the motor with one cycle of thedriving signal is known, thus allowing the rotation of the motor to becontrolled variously. Further, in the case of a lens barrel providedwith a high rotation resolution (traveling distance resolution), byusing the information on the rotation resolution, a driving pitch of thefocus lens can be controlled in accordance with the motor with highprecision. Therefore, although Table 1 shows the example of the divisioninto 8 [sections], a microstep motor with 64 [sections] also can becontrolled, for example.

Further, by using the information on the application voltage of themotor, the application voltage can be set corresponding to variousmotors and driving circuits. Moreover, by using the information on themaximum driving rate such as the motor maximum response frequency andthe maximum self-start frequency, various motors can be controlled atthe maximum rate concerning their focusing.

Further, as shown in Table 2, the information of the operation cycle isprovided as the memory WRITE/READ information. This information can beutilized as information relating to the maintenance of the lens barrel 1such as a timing for replacing the motor 9. For instance, the timing forreplacing the motor 9 can be determined by comparing with theinformation of the maximum operation cycle shown in Table 1, and at thetiming for replacing, this may be displayed. As for maintenance, notonly the information on the operation cycle but information on operationtime may be utilized.

The following describes the reference exciting position at address 0x0Fof FIG. 1 during the process adjustment, with reference to FIG. 37. FIG.37 is a drawing for explaining an origin detection operation during theprocess adjustment according to one embodiment of the present invention.The “exciting position” shown in FIG. 37 corresponds to a phase of thedriving signal, which represents a 3-bit counter value for the excitingposition counter 151 obtained by dividing one cycle of 360 degrees of adriving signal for the motor coil of the motor 9 output from the focusmotor driving unit 11 into 8 sections.

The counter value of the exciting position counter 151 is transmitted tothe motor driving unit 11 via the data transmission/reception units 18and 17. This drawing shows a state where the exciting position isdecreased one by one along with the movement of the focus lens 4 to theimaging device 5 side. By transferring the motor exciting position asaddress 0xA0 (Table 3), the rotation of the motor 9 is controlled.

The “A-phase current” and the “B-phase current” show current waveformsof the motor coil that the focus motor driving unit 11 outputs to themotor 9, and in this example the motor 9 has a two-phase coil with theA-phase and the B-phase. The A-phase current and the B-phase currenthave electrical angles different from each other by the phase of 90° (inthe case where one cycle of the current waveform is 360 degrees), andthe motor 9 is rotated by applying a current to the motor coil with theA-phase and the B-phase. In this drawing, the focus lens 4 moves to theimaging device 5 side while the A-phase current is 90° leading relativeto the B-phase current.

The “absolute position counter” represents a counter value of theabsolute position counter 153, and operates in synchronization with theexciting position. In the case where the exciting position is decreasedone by one, the absolute position counter also is decreased one by one.Herein, the absolute position counter sets a bit width so that the samevalue is not assigned to different positions in the movement range ofthe focus lens 4.

The “photosensor output level” shows the state where the output levelchanges as the focus lens 4 moves to the imaging device 5 side so thatthe photosensor 8 is interrupted by the photo-interruption member 7. The“photosensor output level” is identified by the control unit 13 as “1”in the case of a threshold value or more and “0” in the case of lessthan the threshold value, where data at address 0x20 (Table 3) isidentified via the data transmission/reception units 17 and 18.

Referring now to FIGS. 37 and 38, the origin detection operation of thefocus lens 4 during the process adjustment is described morespecifically. FIG. 38 is a flowchart of the origin detection operationaccording to one embodiment of the present invention, which shows anoperation flow described as a program in the system control unit 13.When the power is turned on in the process adjustment mode, the processstarts with “origin detection adjustment start”.

In Step 221 the motor 9 is shifted to the origin detection direction(the direction of the imaging device 5) by one step at one time. In thiscase, the exciting position counter 151 is decreased one by one. Morespecifically, in response to an instruction from the system control unit13, the exciting position counter 151 is down-counted. In accordancewith this down-counting, the focus motor driving unit 11 outputs adriving signal having periodicity to rotate the motor 9 so as to shiftthe focus lens 4 toward the imaging device 5.

In Step 222, a judgment is made as to whether the photosensor outputlevel exceeds a threshold value or not. In the case of not exceeding,the process returns to Step 221 to make the motor 9 conduct the next onestep operation. In the case of exceeding, the process goes to Step 203,where the exciting position at the time of exceeding is substituted forP. In this case, the exciting position “4′ is substituted for P.

In Step 224, P is stored as P_(O) in the nonvolatile memory 14. Thevalue P_(O) stored in this step is the reference exciting position ofthe motor 9, which is stored as address 0x0F and data 0x04 in thenonvolatile memory 14 via the data transmission/reception unit 18 andthe data transmission/reception unit 17. In Step 225, the absoluteposition counter is reset. In FIG. 5, the position indicated with “0”shows the reset position.

Since this position “0” of the absolute position counter is erased whenthe power is turned off, the origin has to be detected again when thepower supply is turned on in the normal operation mode. For thedetections of this origin, the information stored in the nonvolatilememory 4, i.e., the reference exciting position “4” is used. Since theexciting position “4” is not an absolute value but is at a positionappearing periodically, the origin can be detected by detecting theexciting position “4” corresponding to the origin.

More specifically, in the normal operation mode, the motor 9 is rotatedto the origin detection direction by a signal from the motor controlunit 15. In this case, a judgment is made as to whether the photosensoroutput level exceeds a threshold value or not at the exciting position“0” that is the electrical angle of 180 degrees (½ cycle) of the motor 9away from the reference exciting position “4” that already has beenreceived from the nonvolatile memory 14. If it is judged that thephotosensor output level at a certain judgment position “0” does notexceed the threshold value but the photosensor output level at the nextjudgment position “0” after one cycle exceeds the threshold value, theorigin during the process adjustment can be reproduced accurately. Thatis, the exciting position “4” between these two judgment positions “0”is the origin.

According to this origin detection process, there is no need to detectthe origin directly. Instead, this can be performed simply by judgingthat the photosensor output level at a certain judgment position doesnot exceed the threshold value but the photosensor output level at thenext judgment position after one cycle exceeds the threshold value, asdescribed above. Thus, even if errors occur due to looseness in the lensunit driving direction and variations in mechanism and electricalproperties due to a temperature and humidity change in the operationenvironment, the origin during the process adjustment can be reproducedaccurately.

Note here that a range of errors in looseness in the lens unit drivingdirection and variations in mechanism and electrical properties due to atemperature and humidity change in the operation environment should bewithin the exciting position one cycle.

The following describes a method for controlling the focus lens 4 usingthe focus position correction amount by temperature that is stored inthe nonvolatile memory 14. FIG. 39 is a graph showing the relationshipbetween temperatures and the focus position correction amount. Data ataddress 0x18 of Table 1 is 0x06, and the counter value of the absoluteposition counter 153 changes by six when the temperature changes by 10°C. In this example, correction is made so that the position of the focuslens 4 is shifted closer to (far side) the imaging device 5 along withthe temperature rise, which can be represented with a graph of astraight line having a gradient of −0.6 [counter/° C.] with reference to20° C.

As shown in FIG. 34, the control unit 13 receives information from thetemperature sensor 20. Based on the temperature change detected by atemperature sensor 20 and data 0x06 at address 0x18, the control unit 13corrects the position of the focus lens 4 in accordance with theabove-stated graph, whereby a focus condition can be kept even when atemperature changes.

For instance, in the case where the operation temperature is at 20° C.as the reference temperature, the focus position of the focus lens 4 isnot corrected. On the other hand, when the temperature is at 30° C.,which is higher than the reference temperature by 10° C., the focusposition is corrected at a position closer to the imaging device 5 bythe amount corresponding to the counter value of 6.

The following describes a method for controlling the focus lens 4 usingthe focus position correction amount by attitude angle that is stored inthe nonvolatile memory 14. The relationship between the attitude angleand the output voltage of the angular sensor is as shown in FIG. 17.Data at address 0x19 of Table 1 is 0x1F, and the counter value of theabsolute position counter 153 changes by 31 when the attitude anglechanges by 90°.

In this case, it is assumed that the output voltage of the angularsensor is + when the fixed lens 2 faces upward and the output voltage ofthe angular sensor is − when the fixed lens 2 faces downward. Forinstance, it is assumed that facing upward at 90 degrees results in thechange of focus lens 4 in the direction of closer to the imaging device5 by 31 that is the counter value of the absolute position counter 153due to the looseness of the mechanism, and facing downward at 90 degreesresults in the change of focus lens 4 in the direction of away from theimaging device 5 by 31 that is the counter value of the absoluteposition counter 153 due to the looseness of the mechanism.

As shown in FIG. 34, the control unit 13 receives information from anangular sensor 21. Herein, in the case of facing upward at 90 degrees,for example, based on the angular change detected by the angular sensor21 and data 0x1F at address 0x19, the control unit 13 corrects theposition of the focus lens 4 in the direction away from the imagingdevice 5 by the amount corresponding to the counter value of 31. On theother hand, in the case of facing downward at 90 degrees, the controlunit 13 corrects the position of the focus lens 4 in the directioncloser to the imaging device 5 by the amount corresponding to thecounter value of 31. Thereby, a focus condition can be kept even when anattitude angle changes significantly.

Incidentally, in the case where the looseness in the focus lens position4 is varied between upward and downward relative to the horizontalstate, information therefor may be stored as memory READ information indifferent areas.

The above-description shows the example using the temperature sensor andthe angular sensor. However, a humidity sensor further may be used. Withthis configuration, an error occurring due to a difference inhygroscopic coefficient of the lens barrel and the lens can be improved,thus further enhancing the accuracy.

Further, the above-described embodiments explain the example using astepping motor as the driver. However, this may be other motors as longas an driving signal of the motor has periodicity, and a linear motorfor example may be used.

Moreover, a circuit for detecting the shifting amount of the motor maybe provided, whereby the exciting position counter of the presentembodiment can be counted up or counted down in accordance with theposition. Then, pseudo periodicity can be formed in the driving signal,whereby the present invention is applicable to various motors such as anultrasound motor, a motor made up with a smooth impact drivingmechanism, an electrostatic motor and a piezoelectric motor.

In the present embodiment, the motor for driving the focus lens isdescribed mainly. However, the present invention is applicable to animaging apparatus and a lens barrel having a motor for driving a zoomlens as well.

Embodiment 13

FIG. 40 is a block diagram of an imaging apparatus according toEmbodiment 13. In FIG. 40, numeral 30 denotes a lens barrel, 38 denotesan imaging device and 27 denotes a zoom lens unit as a first lens unitthat is provided to be movable in the lens barrel 30. Numeral 29 denotesa focus lens unit as a second lens unit that is provided to be movableby means of guide poles in the lens barrel 30, which will be describedlater.

Numeral 22 denotes a first driver that drives the zoom lens unit 27 inthe optical axis direction via a movement conveying unit 28, whichincludes a stepping motor, for example. Numeral 23 denotes a seconddriver that drives a stepping motor 35 so as to allow the focus lensunit 29 to be driven in the optical axis direction. Numeral 36 denotes arestriction member (movement restriction unit) with threads cut thereinto mate with a lead screw of the stepping motor 35, which moves in theoptical axis direction along with the rotation of the stepping motor 35.

Numeral 34 denotes a spring that baises the focus lens unit 29 towardthe zoom lens unit 27 side, i.e., a subject side. During the normaloperation of the imaging apparatus, the position of the focus lens unit29 is restricted and kept because a lens frame 29 a thereof is biased bythe spring 34 so as to contact with the restriction member 36.

Numerals 32 and 33 denote guide poles that guide the focus lens unit 29so as to move along the optical axis direction. Numeral 28 denotes amovement conveying unit that is provided for the zoom lens unit 27 andthat contacts the lens frame 29 a of the focus lens unit 29 when thezoom lens unit 27 is shifted in the imaging plane direction.

Numeral 31 denotes a photo-interruption member that is provided for thefocus lens unit 29. As the focus lens unit 29 moves in the imaging planedirection, the photo-interruption member 31 interrupts light of alight-transmission type photosensor 37 (hereinafter called photosensor)attached to the lens barrel 30, whereby the position of the focus lensunit 29 can be detected.

Numeral 24 denotes a controller that outputs a control signal to thefirst driver 22 and the second driver 23 in accordance with an outputsignal of the photosensor 37 and a mode of the imaging apparatus mainbody. Numeral 26 denotes a memory that stores mode information of thecontroller 24, and 25 denotes a signal processor that processes an imageinformation signal output from the imaging device 38. Herein, memory 26as a storage includes a nonvolatile memory or a volatile memory that isdriven by a secondary power supply (not illustrated).

Numeral 39 denotes an internal power supply, for example, provided inthe imaging apparatus, and 40 denotes an external power supply connectedwith a connecting terminal 41. These power supplies allow electric powerto be supplied to the controller 24, the signal processor 25 and thelike when a power supply switch 42 is turned on at the time of the startof an imaging operation. Note here that electric power is supplied fromthe external power supply 40 as an alternative to the internal powersupply 39 when the internal power supply 39 becomes exhausted.

Numeral 43 denotes a termination switch that is connected with thecontroller 24 and that shuts off electric power at the time of thecompletion of the imaging operation. When this termination switch 43 isoperated in the ON state of the power supply switch 42, after thecontroller 24 conducts a predetermined process and operations set forthe time of shutting off the power supply, the controller 24 makes thepower supply switch 42 open to create a power-off state.

Herein, the photosensor 37 making up the above-stated position detectoris attached to the lens barrel 30 and has a U-letter shaped main body. Aphoto-reception element and a photo-transmission element opposed to thephoto-reception element are attached to one strip portion of this mainbody and the other strip portion on the respective inner sides. When thefocus lens unit 29 moves to the imaging device side, thephoto-interruption member 31 enters into a space between thephoto-transmission element and the photo-reception element, so that thelight from the light-transmission element to the light-receptionelement, intersecting at right angles with the optical axis of the lensunits, is interrupted.

FIG. 41 is a drawing for explaining mode transition of the above-statedlens units. Positions of the zoom lens unit 27 and the focus lens unit29 in FIG. 40 for the respective operation modes are separately shown infour drawings of FIGS. 41(a) to (d).

Herein, the controller 24 includes a microcomputer and the like, whichis configured so as to control not only the above-stated operations butalso all operations in this embodiment described herein.

FIG. 42 is an operation flowchart of a process by the controller 24 whenthe power supply switch 42 lets electric power be supplied (ON). Thisshows operation flows in the case where the process is completednormally and abnormally when the operation of the imaging apparatus iscompleted the last time. The abnormal completion refers to the casewhere when electric power is supplied to the imaging apparatus, forexample, when electric power is supplied from the external power supply40, the connecting terminal 41 is detached accidentally, and the powersupply is shut off abruptly.

The memory 26 of FIG. 40 is configured so that, when electric power ofthe imaging apparatus is supplied, an abnormal completion flag is set bythe controller 24 as described later. When the power supply of theimaging apparatus is shut off normally, both of the lens units 27 and 29move, the light of the photosensor 37 is interrupted by thephoto-interruption member 31 and the controller 24 detects that both ofthe lens units 27 and 29 are shifted to their storage positions, thenthe abnormal completion flag is cleared in accordance with aninstruction from the controller 24.

If the operation of the imaging apparatus is not completed normally, forexample, in the case where the power being supplied is shut offabruptly, the light of the photosensor 37 will not be interrupted andboth of the lens units 27 and 29 will not be stored at their storagepositions. In this case, the abnormal completion flag stored in thememory 26 is not cleared. Therefore, this abnormal completion flag ismanaged as a flag that shows the state where the lens units are notstored in the final storage positions in the lens barrel.

As shown in FIG. 42, when electric power is supplied to the imagingapparatus, the controller 24 starts the operation by reading out thepresence or absence of the abnormal completion flag in the memory 26. Ajudgment is made as to whether the process for supplying electric powerduring the normal state or the process for supplying electric powerduring the abnormal state (supplying electric power after abnormalcompletion) is to be conducted, and the process for supplying electricpower is carried out by making a distinction between processes. Thereby,even when the operation of the imaging apparatus is completed abnormallythe last time, the imaging apparatus can be returned to the normal stateby performing the origin detection process of the lens units when theelectric power is supplied to the imaging apparatus next.

FIG. 43 is an operation flowchart of the process for supplying electricpower during the normal state in accordance with an instruction from thecontroller 24, and FIG. 44 is an operation flowchart of the process forsupplying electric power during the abnormal state in accordance with aninstruction from the controller 24. After the operations shown by theflowchart of FIG. 42, the process will proceed in accordance with eitherone of these operations. Herein, in the flowcharts of FIGS. 43 and 44,the zoom lens unit is abbreviated as “zoom” and the focus lens unit isabbreviated as “focus”. These abbreviations are used in the laterdrawings as well.

Firstly, the case where the imaging apparatus is completed normally thelast time and then the imaging apparatus will be operated this time isdescribed below. Before supplying electric power, the zoom lens unit 27and the focus lens unit 29 are stored on the imaging plane side (normalcompletion) as shown in FIG. 41(a) because the operation is completednormally the last time.

In this state, when the power supply switch 42 is turned on and electricpower is supplied to the controller 24 and the like, the operationstarts with the start of the process for supplying electric power ofFIG. 42. In Step 131, the controller 24 reads out the presence orabsence of the abnormal completion flag in the memory 26. Since theabnormal completion flag in the memory 26 is cleared (N) because theoperation is completed normally the last time, the process goes to Step131 a.

In this Step 131 a, the controller 24 sets an abnormal completion flagin the memory 26, and starts the operation of the process for supplyingelectric power during the normal state. That is, since then, theabnormal completion flag is kept to be set, and in the case of normalcompletion, the abnormal completion flag is cleared, or in the case ofabnormal completion, the abnormal completion flag is kept to be set.

On the other hand, in the case where an abnormal completion flag is set(Y) in the memory 26 when electric power is supplied, the process goesto Step 131 b. In this Step 131 b, after an abnormal completion flag isset again, the operation of the process for supplying electric powerduring the abnormal state is started.

Referring to FIG. 43, in the case where the operation of the imagingapparatus is completed normally the last time, the process for supplyingelectric power during the normal state after Step 131 will be describedbelow. In Step 231 of FIG. 43, in accordance with an instruction fromthe controller 24, the first driver 22 drives the zoom lens unit 27 toadvance to the subject side.

As the zoom lens unit 27 moves to advance, the photosensor 37 judgeswhether the light from its light-transmission element to thelight-reception element is transmitted or not in Step 232. In the casewhere the light is not transmitted, the process goes to Step 231 again.Then, as shown in FIG. 41(b), following the advancing movement of thezoom lens unit 27, the focus lens unit 29 moves by the biasing force ofthe spring 34. Along with this, the photo-interruption member 31 moves,so that the photo-interruption state of the photosensor 37 changes intothe photo-transmission state (to the origin position), and the processgoes to next Step 233. In this Step 233, a zoom origin reset process isperformed.

Herein, this origin reset process of the zoom lens unit 27 is performedafter the controller 24 detects that the driving by the first driver 22causes the change of the photo-interruption state of the photosensor 37into the photo-transmission state.

The above-stated origin position detection process is described on theassumption that the first driver 22 is composed including a one-twophase excitation driving stepping motor (not illustrated) as a powersource. In this case, an A-phase current and a B-phase current aresupplied generally for driving the stepping motor, whereby the steppingmotor shifts the zoom lens unit 27 to the advancing direction every 45°electrical angle as shown in the exciting positions of FIG. 46.

The controller 24 monitors the transmission of the light of thephotosensor 37 that changes with the photo-interruption member 31 movingfollowing this movement of the zoom lens unit 27 by means of the outputlevel of the photosensor 37. When the output level exceeds apredetermined threshold value, the absolute position counter is resetand the origin position of the zoom lens unit 27 is detected.

After the zoom origin reset process in the above Step 233, the firstdriver 22 makes the zoom lens unit 27 advance to a wide position, forexample, in Step 234. Along with the advancing movement of the zoom lensunit 27, the focus lens unit 29 also is shifted in the same direction bythe spring 34.

Then, both of the lens units 27 and 29 are shifted from the position ofFIG. 41(a) to the position of FIG. 41(b), so that the lens frame 29 a ofthe focus lens unit 29 contacts with the restriction member 36 at theposition of FIG. 41(b). After this, the zoom lens unit 27 and the focuslens unit 29 are detached, and the zoom lens unit 27 is made to advanceto the wide position as shown in FIG. 41(c).

Next, as shown in Step 235, the second driver 23 drives the steppingmotor 35 so that the restriction member 36 is shifted to the imagingplane side (Far side), whereby the focus lens unit 29 is shifted to theFar side. As a result of the movement of the focus lens unit 29 to theimaging plane side, in Step 236, the controller 24 detects the change ofthe light of the photosensor 37 from the transmission state to theinterruption state due to the photo-interruption member 31.

When the state becomes as shown in FIG. 41(d), the process goes to nextStep 237. Until the focus lens unit 29 moves to the imaging plane sideso as to interrupt the light of the photosensor 37, the process of Step235 and Step 236 will be repeated. When the process goes to Step 237,the controller 24 makes the second driver 23 shift the focus lens unit29 to the subject side (Near side), and then the process goes to Step238.

In Step 238, a judgment is made as to whether the movement of the focuslens unit 29 to the subject side results in the change of the light ofthe photosensor 37 from the interruption state to the transmission stateor not. If the light becomes transmitted, the process goes to next Step239, where the focus origin is detected and focus origin reset isperformed.

This origin reset for the focus lens unit 29 is performed after thecontroller 24 detects that the driving by the second driver 23 causesthe change of the photo-interruption state of the photosensor 37 intothe photo-transmission state, which is distinguished from the case ofthe zoom lens unit 27 where the interruption state of the light of thephotosensor 37 is changed into the transmission state by the driving ofthe first driver 22. Until the focus lens unit 29 moves to the imagingplane side so as to interrupt the light of the photosensor 37, theprocess of Step 237 and Step 238 will be repeated.

The following describes the origin detection process of the focus lensunit 29. FIG. 46 is a drawing for explaining the operation for theorigin detection of the lens unit. This drawing shows the example wherea A-phase current and a B-phase current are supplied from the driver 23to the one-two phase excitation driving stepping motor 35, and drivingby electrical angle of 45 degrees is carried out for each step as shownin the exciting positions of 0 to 7 so that the focus lens unit 29 isdriven toward the subject side.

The output level of the photosensor 37 is monitored by the controller24. When the output level exceeds a predetermined threshold value, theabsolute position counter is reset, whereby the origin of the focus lensunit 29 is detected, so that the process for supplying electric power iscompleted.

After the completion of the above process for supplying electric power,in accordance with an operation by the operator of the imagingapparatus, the controller 24 is controlled so as to drive the both lensunits 27 and 29 to perform the imaging operation.

The following describes the operation for the abnormal completion, forexample, while electric power is supplied to the imaging apparatusduring the last time operation, the electric power is shut offaccidentally. As the state of the lens units when the operation iscompleted abnormally the last time, any state of FIGS. 41(a) to (d) ispossible.

FIG. 41(a) shows the abnormal completion state in the case wherealthough the lens units 27 and 29 are stored normally, the power supplyis shut off forcibly before the completion of all storage operation, andthe abnormal completion flag in the memory 26 is not cleared but stillremains set. FIG. 41(d) shows the case where the power supply is shutoff during the normal operation of the imaging apparatus (e.g., duringimage capturing).

In both of the states of FIG. 41(a) and FIG. 41(d), the light of thephotosensor 37 is interrupted by the photo-interruption member.Therefore, when electric power is supplied, a judgment cannot be madeonly from the state of the photosensor 37 as to at which one of thestates in the last time operation the abnormal completion is made.

FIG. 41(b) shows the state where the power supply is shut off during theadvancing or collapsing operation of the zoom lens unit 27 (the statewhere the movement conveying unit 28 contacts with the lens frame 29 aof the focus lens unit 29). FIG. 41(c) shows the state the power supplyis shut off during the normal operation of the imaging apparatus (e.g.,during image capturing). In both of the states of FIG. 41(b) and FIG.41(c), the light of the photosensor 37 is transmitted. Therefore, whenelectric power is supplied, a judgment cannot be made in both of thestates as to identifying which one of the states in the last timeoperation the abnormal completion is made.

Therefore, according to this embodiment, when electric power issupplied, an abnormal completion flag in the memory 26 is read out. Ifthe abnormal completion flag is set in the memory 26, “the process forsupplying electric power during the abnormal state” firstly is carriedout and then “the process for supplying electric power during the normalstate” is carried out. On the other hand, if the abnormal completionflag is cleared, “the process for supplying electric power during thenormal state” is carried out as stated above.

From this, in the case of the normal state, the imaging apparatus can bemade ready for imaging quickly without undergoing the process for theabnormal state. In the case of the abnormal state, by inserting theprocess for abnormal state before the process for normal state, theabnormal state can be recovered to the stable state.

Referring to FIG. 44, the process when electric power is supplied (ONstate) by the power supply switch 42 and the like after the abnormalcompletion state will be described below. In Step 331, the controller 24judges whether light is transmitted from the light-transmission elementto the light-reception element of the photosensor 37 or not. In the caseof FIGS. 41(b) and (c) where the photosensor 37 is in thelight-transmission state, the process goes to Step 336. In Step 336, thefirst driver 22 shifts the zoom lens unit 27 to the imaging plane side(Far side) to perform the collapsing operation.

In the case of FIGS. 41(a) and (d) where the light of the photosensor 37is interrupted by the photo-interruption member 31, the process goes toStep 332, where the first driver 22 makes the zoom lens unit 27 advance.When the zoom lens unit 27 advances, the controller 24 in Step 333detects whether the photosensor 37 is in the light-transmission statefrom the light-transmission element to the light-reception element ornot. In the case where the light of the photosensor 37 is nottransmitted as a result of the advancing operation of the zoom lens unit27, the process goes to Step 333 a, where a judgment is made as towhether the zoom lens unit 27 finishes the movement of a distance in apredetermined amount of (Y1+α) or not.

Herein, the relationship between the storage position of the zoom lensunit 27 in the collapsing state and the origin (the position of thetransition from the interruption state to the transmission state of thelight of the photosensor 37) will be described below. Along with thestorage operation of the zoom lens unit 27 by collapsing, the focus lensunit 29 also moves in the same direction. Along with the movement of thefocus lens unit 29, the photo-interruption member 31 also moves so thatthe light of the photosensor 37 changes from the transmission state tothe interruption state at the origin.

The storage position of the zoom lens unit 27 is set at a furthercollapsing position. The position shifted by the distance correspondingto the pulse number of the stepping motor of 2 pulses in the collapsingdirection is the storage position. Therefore, when the zoom lens unit 27advances from the storage position by three pulses, then it reaches theorigin where the light of the photosensor 37 changes from thelight-interruption state to the transmission state.

Since the zoom lens unit 27 is configured so as to have the above-staterelationship of the storage position and the origin, the above-stated Y1becomes (origin)—(storage position) and α is set at a distancecorresponding to the pulse number of the stepping motor of 1 pulse, forexample. Thereby, in Step 333 a, the controller 24 judges whether thezoom lens unit 27 finishes the movement corresponding to 1 pulse of thepulse number of the stepping motor after the passage of the origin. Thisjudgment equals to the judgment of the movement of (Y1+α) from thestarting position of the advancing operation of the zoom lens unit 27.In Step 333 a, when the controller 24 a detects the completion of themovement of (Y1+α), then the process goes to Step 334.

The process changes from Step 333 a to Step 334 in the case wherealthough the zoom lens unit 27 moves by (Y1+α), the photosensor 31 stillremains in the interruption state. Such a state occurs when the movementof the focus lens unit 29 is restricted by the restriction member 36 asshown in FIG. 41(d).

In Step 334, the second driver 23 shifts the focus lens unit 29 to thesubject side (Near side). Thereby, the photo-interruption member 31 alsomoves, and when it is detected in Step 335 that the photosensor 37 is inthe light-transmission state, the movement of the focus lens unit 29 isstopped, and the process goes to Step 336. In this Step 336, the firstdriver 22 is operated so as to start the collapsing operation of thezooming lens unit 27.

In the collapsing operation of the zooming lens unit 27 to the imagingplane side in Step 336, during the time when the light of thephotosensor 37 is judged as the transmission state in Step 337, thecollapsing operation will be continued. When the light of thephotosensor 37 is interrupted by the photo-interruption member 31 andthe origin is detected, the process goes to Step 338.

In Step 338, when the completion of the movement of the distance in theabove-stated predetermined amount of Y1 is detected, the process forsupplying electric power during the abnormal state is completed. In thisstate, the zoom lens unit 27 reaches the storage position shown in FIG.41(a). After this, the process changes to the process for supplyingelectric power during the normal state as shown in FIG. 43, where thesetting for making the apparatus ready for imaging is carried out.Herein, in this transition to the process for supplying electric powerduring the normal state, the abnormal completion flag reset in thememory 26 is left as it is. After this, the abnormal completion flag iskept to be set, and in the case of normal completion, the abnormalcompletion flag is cleared, whereas in the case of abnormal completion,the abnormal completion flag will be kept to be set.

As stated above, according to the present embodiment, even in the casewhere the imaging apparatus is completed abnormally the last time, theabnormal completed state can be recovered to change to the normal andusual process for supplying electric power during the normal state.

Referring to FIG. 45, the process for the normal shut-off of the powersupply by an operator after the normal imaging operation will bedescribed below. After the completion operation by shutting off theelectric power by the termination switch 43, firstly in Step 431, thecontroller 24 judges whether the light of the photosensor 37 istransmitted from the light-transmission element to the light-receptionelement or not.

In the case where the photo-interruption member 31 prevents the lightfrom being transmitted through the photosensor 37, the process goes toStep 431 a. In Step 431 a, the second driver 23 shifts the focus lensunit 29 toward the subject, and the process goes to Step 431 b. In Step431 b, the controller 24 judges whether, as a result of the movement ofthe focus lens unit 29, the light of the photosensor 37 is transmittedor not. If the transmission of the light is detected as a result of themovement of the photo-interruption member 31, the movement of the focuslens unit 29 is stopped, and the process goes to next Step 432.

In Step 432, the first driver 22 drives and shifts the zoom lens unit 27to the imaging plane side so as to perform a collapsing operation. Asthe zoom lens unit 27 moves to the imaging plane side in this way, thefocus lens unit 29 also moves to the imaging plane side. Then, in Step433, a judgment is made as to whether the light of the photosensor 37 istransmitted or not. In the case where the light is transmitted, theprocess returns to Step 432 to continue the collapsing operation, and ifit is detected that the transmission of the light is interrupted, theprocess goes to Step 434.

The position where the light of the photosensor 37 is interrupted is theorigin, and the focus lens unit 29 is shifted by the zoom lens unit 27to a storage position that is shifted by the above-stated predeterminedamount of Y1 from this origin. In Step 434, a judgment is made as towhether the collapsing operation is completed to arrive at this storageposition. In Step 434, if the collapsing operation is not completed, theprocess returns to Step 432 to continue the collapsing operation, so asto shift the zoom lens unit 27 securely to the storage position shown inFIG. 41(a).

In Step 434, it is detected that the zoom lens unit 27 arrives at theposition shifted by the predetermined amount of Y1 from the origin,i.e., at the storage position, so that the collapsing operation iscompleted, the abnormal completion flag in the memory 26 is cleared inStep 435, and the controller 24 turns the power supply switch 34 off,which means the completion of the process for shutting off the powersupply.

Note here that the completion of the collapsing operation, i.e., themovement of the zoom lens unit 27 to the storage position, can bedetected by the application of two pulses to the stepping motor makingup the first driver 22 after the detection of the origin of the zoomlens unit 27 and the completion of the application of one further pulseto the stepping motor after the movement by the predetermined amount ofY1.

That is the explanation of the present embodiment. The features of thepresent embodiment can be summarized as follows: in the operation forsupplying electric power during the normal state, the controller 24firstly reads out an abnormal completion flag from the memory 26 andconfirms that the flag is cleared. At the time of this confirmation, thelens units are positioned as in the state of FIG. 41(a), and it isjudged as the storage completion state.

Next, from the state of FIG. 41(a), the first driver 22 makes the zoomlens unit 27 perform an advancing operation, so that the focus lens unit29 stored by this zoom lens unit 27 is advanced together with this zoomlens unit 27 by the returning force of the spring 34. Along with this,the photo-interruption member 31 also moves, so that the photosensor 37changes from the light-interruption state to the light-transmissionstate. By detecting the changing point from the light-interruption stateto the transmission state, the origin of the zoom lens unit 27 is reset.

Next, the zoom lens unit 27 further is shifted so as to advance to apredetermined position, and as shown in FIG. 41(c), in the state wherethe movement conveying unit 28 is detached from the lens frame 29 a ofthe focus lens unit 29, the focus lens unit 29 is shifted toward theimaging device 38 by driving the stepping motor 35.

Thereafter, after the photosensor 37 is interrupted by thephoto-interruption member 31 once, the stepping motor 35 isreverse-driven to shift the focus lens unit 29 toward the subject by thebiasing force of the spring 34. As a result, the position where thephotosensor 37 changes from the light-interruption state to thelight-transmission state due to the photo-interruption member 31 isdetected, whereby the origin of the focus lens unit 29 is reset. Whenelectric power is supplied during the normal time, the above-statedoperation enables the origin detection of the respective lens unitsusing one photosensor 37.

The following describes the operation in the case where electric poweris supplied after the abnormal completed state, for example, whileelectric power is supplied to the imaging apparatus during the last timeoperation, the power supply is shut off accidentally. Firstly, thecontroller 24 reads out an abnormal completion flag from the memory 26,and if this abnormal completion flag is set, it is judged that theshut-off of the power supply is not performed normally and the lensunits have not been stored completely (abnormal completion state).

At the time when this abnormal completion flag is confirmed, it isunknown at which state of (a), (b), (c) and (d) of FIG. 41 therespective lens units are located. Further, in the case where the lensunits have not been stored completely, if the light of the photosensor37 is interrupted, it is unknown whether the photosensor 37 isinterrupted by the photo-interruption member 31 resulting from thedriving of the zoom lens unit 27 by the first driver 22 or isinterrupted by the photo-interruption member 31 by the focus lens unit29.

Therefore, in order to allow the transition from the abnormal completionstate to the process for supplying electric power during the normalstate, a judgment is made firstly as to whether the light of thephotosensor 37 is transmitted or not, which is for locating therespective lens units. In the case where the light is transmitted, thezoom lens unit 27 is made to collapse so that the light of thephotosensor 37 is interrupted by the photo-interruption member 31.Thereby, it can be found that the movement of the zoom lens unit 27 bythe first driver 22 causes the interruption of the light of thephotosensor 37, thus enabling the transition to the process forsupplying electric power during the normal state.

On the other hand, in the case where the light of the photosensor 37 isnot transmitted, the zoom lens unit 27 is made to advance by apredetermined amount by the first driver 22. If this operation allowsthe light of the photosensor 37 to be transmitted, it can be found thatthe light of the photosensor 37 is interrupted due to the movement ofthe zoom lens unit 27 by the first driver 22 at the time of the abnormalcompletion. Therefore, in this case, after making the zoom lens unit 27advance, then the zoom lens unit 27 is made to collapse so that thelight of the photosensor 37 is interrupted, thus enabling the transitionto the process for supplying electric power during the normal state.

If the light of the photosensor 37 is not transmitted even when the zoomlens unit 27 is made to advance by the predetermined amount, it isestimated that since the focus lens unit 29 cannot move by the returningforce of the spring 34, the light of the photosensor 37 is interruptedby the photo-interruption member 31. Therefore, the focus lens unit 29is shifted toward the subject by the second driver 23, and after thetransmission of the light of the photosensor 37 is confirmed, then thezoom lens unit 27 is made to collapse by the first driver 22, thusenabling the transition to the process for supplying electric powerduring the normal state.

Next, the operation for shutting off the power supply is as follows. Forexample, when the collapsing operation of the zoom lens unit 27 isperformed by the driving by the first driver 22 from the state where thelight of the photosensor 37 is not transmitted by the photo-interruptionmember 31 of the focus lens unit 29 as shown in FIG. 41(c), the movementconveying unit 28 of the zoom lens unit 27 contacts with the lens frame29 a of the focus lens unit 29. Thereby, the focus lens unit 29integrally moves to the imaging plane side against the spring 34, sothat the photosensor 37 changes from the light-transmission state to thelight-interruption state by the photo-interruption member 31. Inresponse to the detection of this change of states, the collapsingoperation is completed and the lens units are stored.

Herein, in the case where the power-supply shut-off operation isperformed in the state where the light of the photosensor 37 isinterrupted by the photo-interruption member 31 of the focus lens unit29 as shown in FIG. 41(d), the stepping motor 35 is driven firstly sothat the focus lens unit 29 is shifted to the subject side by thebiasing force of the spring 34.

With this operation, the photosensor 37 is made in thelight-transmission state once, and based on the detection of the changeof the states of the photosensor 37, the collapsing operation of thezoom lens unit 27 is performed by driving of the first driver 22 fromthe state of the light-transmission state of the photosensor 37, wherebythe lens units are stored at their storage positions.

Then, when these lens units are shifted to their storage positions andthe collapsing operation is completed, the power supply is shut off. Inthis way, the above-stated operation is performed for shutting of thepower supply, thus enabling the origin detection of the lens units whenelectric power is supplied next.

As stated above, according to the present embodiment, the origins of thefirst lens unit (zoom lens unit) and the second lens unit (focus lensunit) can be detected using a common position detector using onephotosensor. That is, the position detector allows not only the origindetection of the second lens unit but also the origin detection of thefirst lens unit by shifting resulting from the contact of the first lensunit with the second lens unit. Thereby, the number of components can bedecreased, and the lens barrel can be miniaturized in the optical axisdirection and in the outer rim direction.

Further, even in the case of the abnormal stopping where electric poweris supplied by externally connecting a connecting terminal with theimaging apparatus and such power supply is shut off abruptly by theconnecting terminal falling off, for example, the origin detectionprocess can be performed normally and the apparatus can be returned tothe normal state when electric power is supplied the next time.

The above-described embodiment is just one example, and a methodincluding a storage that stores information varied depending on thenormal completion state in which a first lens unit and a second lensunit are shifted to their storage positions from the power-supply statein accordance with predetermined processes and operations when electricpower supplied is shut off and the abnormal completion state that iscompleted in a state different from the normal completion state in thepower-supply state, the method being for returning the first lens unitand the second lens unit to the normal completion state in accordancewith the information stored in the storage when electric power is to besupplied after the abnormal completion state, can be embodied with otherconfigurations similarly.

Further, as another configuration, when power is turned on in theabnormal completion state, the process may be completed simply byreturning to the normal completion state, and the apparatus may bestopped in this state. In this case, when electric power is suppliedagain, the process for supplying electric power during the normal statecan be performed.

Further, in the case where a secondary power supply is used as a powersupply for the storage, and in the case where the storage includes avolatile memory, a reduction in the secondary power supply may cause aloss of the abnormal completion information. In such a case, however,the abnormal completion can be judged by detecting the reduction in thepower supply, so that the apparatus can be returned to the normal statewithout malfunction.

Further, the movement conveying unit and the movement restriction unit(in this embodiment, the movement conveying unit 28 and the restrictionmember 36) for controlling the movement of the second lens unit may bebrought into contact with each other at a position where they are closerto the lens frame of the second lens unit. Thereby, the portion of thelens frame that should be reinforced in strength because of the contactcan be reduced in area, and the portion of the contacting face whoseprofile irregularity should be secured also can be made smaller.Therefore, the stable operation is enabled, and there is substantiallyno torsion in the second lens unit even when a contacting force isapplied thereto because the portion contacting with the lens frame isbrought closer to the supporting members (in this embodiment, guidepoles 32 and 33) supporting the second lens unit movably, whereby thesecond lens unit can move smoothly. Herein, the number of the supportingmembers is not limited to two and more supporting members may beprovided.

Further, the present embodiment describes the example using the steppingmotor as the driver for driving the first lens unit (the zoom lens unit)and the second lens unit (the focus lens unit). However, a DC motor, anultrasound motor and the like may be used for the driver, and they arenot limited specifically. They may be a motor with an encoder or a motorwithout an encoder.

The predetermined amount Y1 that is the amount of shifting the lens unitto the storage position by way of the origin may be a distance based onthe time in accordance with timer setting, for example, or apredetermined amount based on other settings.

Further, in the present embodiment, after shifting the lens unit to thestorage position, one pulse is applied to the stepping motor. However,still more pulses may be applied, or no pulse may be applied after theshifting to the storage position.

Further, the present embodiment describes the example using atransmission type photosensor and a photo-interruption member (member tobe detected) as the position detector for detecting the origin. However,a reflective type photosensor and a reflection member may be used.Alternatively, a hall device and a magnet may be used.

Moreover, the method for detecting the origin of the first lens unit isnot limited to the present embodiment, including the movement conveyingunit that is directly attached to or integrally molded with the firstlens unit, i.e., the movement conveying unit that moves integrally withthe first lens is brought into contact with the second lens unit. Morespecifically, other movement conveying units, provided so as to move tobe linked with the first lens unit, e.g., a movement conveying unit thatis shifted by the first driver and is provided in the shifting meansthat shifts the first lens unit, also is possible.

Further, the movement conveying unit that makes the first lens unit andthe second lens unit move to be linked with each other may include oneprovided on the second lens unit side.

Although the movement conveying unit described in the present embodimentcontacts at one point, it may contact at two or more points or contactwith a large plane.

Embodiment 14

FIG. 47 includes a schematic diagram and a block diagram of an imagingapparatus according to Embodiment 14. In FIG. 47, a first lens group 2,a second lens group 3 and a third lens group 4 (hereinafter the thirdlens group is called “focus lens”) are disposed in a barrel 1. A stop160 adjusts a light amount of light of a subject passing through thefirst lens group 2 and the second lens group 3. An imaging device 5captures an image of the light of the subject passing through therespective lens groups.

A contacting member 60 is fixed to a frame 152 of the focus lens 4, andthe position of the contacting member 60 is restricted by a restrictionmember 70. Along with the rotation of a focus motor 150, a lead screw151 with threads cut therein rotates so that the frame 152 moves towardthe imaging device 5 until the contacting member 60 contacts with therestriction member 70, thus restricting the movement of the focus lens 4toward the imaging device 5.

An image of the subject received by the imaging device 5 is processed bya signal processing unit 12. In a system control unit 100, in accordancewith an operation signal of operation buttons 101 such as a shutterbutton and a power supply button of a camera main body and menu buttons(not illustrated) and an image signal output from the signal processingunit 12, control information for the focus lens 4 and the stop 160 istransmitted/received to/from a control circuit 200.

Herein, the focus motor 150 is a stepping motor. The stop 160 isprovided with a stepping motor (hereinafter called “iris motor”) thatdrives blades for adjusting the light amount, which will be describedlater.

A focus driver 400 and an iris driver 500 are pulse generation circuitsthat generate pulses of a driving current (hereinafter called “drivingpulses)” for driving the stepping motors. The control circuit 200 isprovided with an I/F unit 205 that transmits control informationtransmitted from the system control unit 100 to the focus driver 400 andthe iris driver 500. Further, a calculation unit 201 that calculatescontrol information for controlling the focus lens 4 and the stop 160, acounting unit 202, an origin storage unit 203 and an offset storage unit204 are provided.

FIG. 48 is a detailed block diagram of the control circuit 200 in theimaging apparatus according to the present embodiment. In FIG. 48, thecounting unit 202 includes an exciting position counter 210 that countsexciting positions of the focus motor 150 and an absolute positioncounter 211 that is reset or present by an origin reset processdescribed later and counts an absolute position of the focus motor 150.Further, an exciting position counter 212 that counts exciting positionsof an iris motor 160 a (described later) and an absolute positioncounter 213 that is reset or present by an origin reset processdescribed later and counts an absolute position of the iris motor 160 aare provided.

In accordance with an instruction for driving the focus motor and aninstruction for driving the iris motor that are sent from the I/F unit205, the calculation unit 201 counts up and counts down the excitingposition counters 210 and 212 based on the information of the countingunit 202, the origin storage unit 203 and the offset storage unit 204,and reads out counter values of the respective exciting positioncounters. Further, the calculation unit 201 resets or presets theabsolute position counters 211 and 213 and reads out counter values ofthe respective absolute position counters.

FIG. 49 is a block diagram of a motor unit and a focus driver of theimaging apparatus according to the present embodiment. In FIG. 49,numeral 400 denotes the focus driver, 150 a denotes an A-phase coil, 150b denotes a B-phase coil, 150 c denotes a rotor magnetized to have twopoles, 60 denotes a contacting member and 70 denotes a restrictionmember.

In FIG. 47, the example is described where the contacting member 60 issecured to the focus lens 4 and the restriction member 70 is restrictedby the barrel 1. This holds true, but in FIG. 49 for the sake ofclarity, the example where the contacting member 60 is attached to therotor 150 c and the restriction member 70 is disposed closer to therotor 150 c is described below.

In the example of FIG. 47, the contacting member 60 shown with the solidline is located at a position displaced from the position of therestriction member 70 toward the stop 160. As described above, as thefocus lens 4 moves toward the imaging device 5 along with the rotationof the focus motor 150, the contacting member 60 will contact with therestriction member 70 as shown with the broken line. The position of thecontacting member 60 in FIG. 49 corresponds to the position of thecontacting member 60 shown with the solid line in FIG. 47. As the rotor150 c rotates to the right, the contacting member 60 contacts with therestriction member 70. This position corresponds to the position of thecontacting member 60 shown with the broken line in FIG. 47.

The following describes the driving control of the stepping motor basedon the example of FIG. 49. FIG. 50 is a timing chart showing a currentpattern of the exciting currents applied to the A-phase coil and theB-phase coil of the motor unit of the imaging apparatus according to thepresent embodiment. The motor unit is a stepping motor driven by aso-called one-two phase excitation method.

The one-two phase excitation method type stepping motor is driven by thecombination of the application of a control current with two polaritiesof positive and negative to the A-phase coil 150 a and the applicationof a control current with two polarities of positive and negative to theB-phase coil 150 b. Herein, three patterns of the application of thecurrent to the A-phase coil 150 a can be considered including theapplication of a positive current (A+), the application of a negativecurrent (A−) and the case of none of them applied (0).

Also, three patterns of the application of the current to the B-phasecoil 150 b can be considered as well, including the application of apositive current (B+), the application of a negative current (B−) andthe case of none of them applied (0). Therefore, the possibleapplication patterns of the currents are 9 patterns=3 patterns×3patterns, but the pattern in which currents are not applied to theA-phase or the B-phase should be excluded, so that they are 8 patternsin total.

The timing chart of FIG. 50 shows 8 current patterns with the excitingposition numbers from 0 to 7. The respective exciting position numberscorrespond to the following current patterns. The current patterncorresponding to the following exciting position numbers from 0 to 7 isapplied to the stepping motor successively, so that the stepping motoris driven to rotate.

(a) exciting position number 0: (A-phase, B-phase)=(A−, 0)

(b) exciting position number 1: (A-phase, B-phase)=(A−, B−)

(c) exciting position number 2: (A-phase, B-phase)=(0, B−)

(d) exciting position number 3: (A-phase, B-phase)=(A+, B−)

(e) exciting position number 4: (A-phase, B-phase)=(A+, 0)

(f) exciting position number 5: (A-phase, B-phase)=(A+, B+)

(g) exciting position number 6: (A-phase, B-phase)=(0, B+)

(h) exciting position number 7: (A-phase, B-phase)=(A−, B+)

FIG. 51 is a schematic diagram showing the relationship between theexciting positions of the motor unit and the driving positions when thecontracting member 60 is brought closer to the restriction position froma position away from the restriction position by advancing the excitingposition number one by one in the imaging apparatus according to thepresent embodiment. FIGS. 51(a) to (h) correspond to the above-statedexciting position numbers from 0 to 7. These drawings are viewed fromthe rotation axis direction of the rotor 150 c of the stepping motor,and the A-phase coil 150 a and the B-phase coil 150 b are disposed atpositions displaced by 90 degrees from each other in the rotationdirection of the rotor 150 c.

In the case of corresponding to the exciting position number 0, currentis not applied to the B-phase coil 150 b and current is applied to theA-phase coil from the A− terminal to the A+terminal. Therefore, theA-phase coil 150 a is excited as the S-pole attracting the N-pole of therotor 150 c, so that the rotor 150 c is kept at the position of FIG.51(a).

In the case of corresponding to the exciting position number 1, currentis applied to the A-phase coil 150 a from the A− terminal to the A+terminal, and current is applied to the B-phase coil 150 b from the B−terminal to the B+ terminal. Therefore, the N-pole of the rotor 150 c isattracted by the both coils excited as the S-pole, so that the rotor 150c is kept at the position of FIG. 51(b) where the respective attractiveforces are balanced.

In the case of corresponding to the exciting position number 2, currentis not applied to the A-phase coil 150 a and current is applied to theB-phase coil 150 b from the B− terminal to the B+ terminal. Therefore,the B-phase coil 150 b is excited as the S-pole attracting the N-pole ofthe rotor 150 c, so that the rotor 150 c is kept at the position of FIG.51(c).

In the case of corresponding to the exciting position number 3, currentis applied to the A-phase coil 150 a from the A+ terminal to the A−terminal, and current is applied to the B-phase coil from the B−terminal to the B+ terminal. Therefore, the A-phase coil 150 a excitedas the N-pole attracts the S-pole of the rotor 150 c and the B-phasecoil 150 b excited as the S-pole attracts the N-pole of the rotor 150 c,so that the rotor 150 c is kept at the position of FIG. 51(d) where therespective attractive forces are balanced.

In the case of corresponding to the exciting position number 4, currentis not applied to the B-phase coil 150 b and current is applied to theA-phase coil 150 a from the A+ terminal to the A− terminal. Therefore,the A-phase coil 150 a is excited as the N-pole attracting the S-pole ofthe rotor 150 c, so that the rotor 150 c is kept at the position of FIG.51(e).

In the case of corresponding to the exciting position number 5, currentis applied to the A-phase coil 150 a from the A+ terminal to the A−terminal, and current is applied to the B-phase coil from the B+terminal to the B− terminal. Therefore, the S-pole of the rotor 150 c isattracted by the both coils excited as the N-pole, so that the rotor 150c is kept at the position of FIG. 51(f) where the respective attractiveforces are balanced.

In the case of corresponding to the exciting position number 6, currentis not applied to the A-phase coil 150 a and current is applied to theB-phase coil 150 b from the B+ terminal to the B− terminal. Therefore,the B-phase coil 150 b is excited as the N-pole attracting the S-pole ofthe rotor 150 c, so that the rotor 150 c is kept at the position of FIG.51(g).

In the case of corresponding to the exciting position number 7, currentis applied to the A-phase coil 150 a from the A− terminal to the A+terminal, and current is applied to the B-phase coil 150 b from the B+terminal to the B− terminal. Therefore, the A-phase coil 150 a excitedas the S-pole attracts the N-pole of the rotor 150 c and the B-phasecoil 150 b excited as the N-pole attracts the S-pole of the rotor 150 c,so that the rotor 150 c is kept at the position of FIG. 51(h) where therespective attractive forces are balanced.

When the state of the exciting position number 0 changes into the stateof the exciting position number 1, the rotor 150 c receives a thrustrotating to the right from the position of the exciting position number0 and assumes the state of the exciting number position 1. When thestate of the exciting position number 1 changes into the state of theexciting position number 2, the rotor 150 c receives a thrust rotatingto the right from the position of the exciting position number 1 andassumes the state of the exciting number position 2. After that, as theexciting position number is advanced one by one, the rotor 150 c willrotate to the right. Herein, the exciting position number 0 follows theexciting position number 7.

In this way, the stepping motor is driven to rotate. Since the A-phasecoil 150 a and the B-phase coil 150 b are disposed at positionsdisplaced by 90 degrees from each other in the rotation direction of therotor 150 c, this stepping motor has a resolution of a half of 90degrees that is the displacement pitch of the coil, i.e., a 45-degreeresolution.

FIG. 52 is a schematic diagram showing the relationship between theexciting positions of the motor unit and the driving positions when theexciting position number is advanced further one by one from the stateof FIG. 51(h). As stated above, as the rotor 150 c rotates to the rightfrom the exiting position number 0 to the exiting position number 7 inthis order in FIG. 51, the contacting member 60 is restricted by therestriction member 70 at the position of FIG. 51(h). Therefore, in thisstate, the rotor 150 c no longer rotates even if the thrust for rotatingto the right is applied to the rotor 150 c.

Therefore, when the exciting position number is advanced from 7 to 0,the rotor 150 c does not rotate, and as shown in FIG. 52(a), the rotor150 c keeps the position of FIG. 51(h). If the contacting member 60 wasnot restricted by the restriction member 70, the rotor 150 c wouldrotate to the position of FIG. 51(a).

In the state of FIG. 52(a), the thrust that makes the rotor 150 c rotateto the right acts on the rotor 150 c. That is, the contacting member 60pushes the restriction member 70 in the direction shown by the arrow ofthe drawing.

Even when the exciting position number is advanced to 1, as shown inFIG. 52(b), the rotor 150 c does not rotate and keeps the formerposition. If the contacting member 60 was not restricted by therestriction member 70, the rotor 150 c would rotate to the position ofFIG. 51(b). Also in the state of FIG. 52(b), the thrust that makes therotor 150 c rotate to the right acts on the rotor 150 c. That is, thecontacting member 60 pushes the restriction member 70 in the directionshown by the arrow of the drawing.

Even when the exciting position number is advanced to 2, as shown inFIG. 52(c), the rotor 150 c does not rotate and keeps the formerposition. If the contacting member 60 was not restricted by therestriction member 70, the rotor 150 c would rotate to the position ofFIG. 51(c). Also in the state of FIG. 52(c), the thrust that makes therotor 150 c rotate to the right acts on the rotor 150 c. That is, thecontacting member 60 pushes the restriction member 70 in the directionshown by the arrow of the drawing.

When the exciting position number is advanced to 3, the following twopatterns can be considered: the former state is kept as shown in FIG.52(d), and the rotor 150 c rotates to the position shown in FIG. 51(d).The reason for this is as follows. When the exciting position numbersare 0 to 2, the A-phase coil 150 a or the B-phase coil 150 b is excitedto have the pole such that the thrust making the rotor 150 c rotate tothe right acts.

On the other hand, when the exciting number position is 3, the A-phasecoil 150 a is excited as the N-pole and the B-phase coil 150 b isexcited as the S-pole, and in the state of FIG. 52(d), the rotor 150 creceives repulsion forces from both coils uniformly, so that the rotor150 c is in an instable state.

Therefore, if the magnetic force of the B-phase coil 150 b is evenslightly stronger than the magnetic force of the A-phase coil 150 a, orconversely if the magnetic force of the A-phase coil 150 a is evenslightly stronger than the magnetic force of the B-phase coil 150 b, orif vibration is applied externally, the rotor 150 c may rotate to theleft to be kept in the state shown in FIG. 51(d). That is, in thisstate, the rotor 150 c may be located at either one of the two positionsof FIG. 52(d) and FIG. 51(d), thus showing an instable state.

FIG. 52(e) shows the state where the rotor 150 c changes from therestricted state (upper one) to the state of the exciting positionnumber of 4 (lower one). When the exciting position number is 4, theA-phase coil 150 a is excited as the N-pole and the B-phase coil 150 bis not excited. Therefore, the rotor 150 c rotates from the positionshown in the upper one to the left and is kept at the position shown inthe lower one.

FIG. 52(f) shows the state where the rotor 150 c changes from therestricted state (upper one) to the state of the exciting positionnumber of 5 (lower one). When the exciting position number is 5, theA-phase coil 150 a and the B-phase coil 150 b are excited as the N-pole.Therefore, the rotor 150 c rotates from the position shown in the upperone to the left and is kept at the position shown in the lower one.

FIG. 52(g) shows the state where the rotor 150 c changes from therestricted state (upper one) to the state of the exciting positionnumber of 6 (lower one). When the exciting position number is 6, theA-phase coil 150 a is not excited and the B-phase coil 150 b is excitedas the N-pole. Therefore, the rotor 150 c rotates from the positionshown in the upper one to the left and is kept at the position shown inthe lower one.

In the state with the exciting position number of 7 shown in FIG. 52(h),the rotor 150 c is kept at the position where the contacting member 60contacts with the restriction member 70. That is, the state of FIG.52(h) is an ideal state, where the force keeping the rotor 150 c at thatposition acts on the rotor 150 c, and at the position where the rotor150 c is kept, the contacting member 60 just contacts with therestriction member 70. In this state, there is no force acting so thatthe contacting member 60 pushes the restriction member 70. However, ifthe restriction member 70 is displaced to the left even slightly, thecontacting member 60 will be pushed toward the restriction member 70. Inthis case, the thrust will act on the rotor 150 c so as to make therotor 150 c rotate to the right.

In this way, in the case where the rotor 150 c contacts with therestriction position, the direction of the magnetic force acting on therotor magnet varies in accordance with the exciting position number.FIG. 53 schematically shows the relationship between the directions ofthe forces that the rotor magnet of the imaging apparatus according tothe present embodiment receives and the exciting position numbers. Inthe case where the rotor 150 c contacts with the restriction position,in the state with the exciting position numbers of 7 and 3, the magneticrotation thrust does not acts on the rotor magnet as described above.

When the exciting position numbers are 0 to 2, the magnetic force actson the rotor magnet so as to push it in the direction of the restrictionposition. Conversely, when the exciting position numbers are 4 to 6, themagnetic force acts on the rotor magnet so as to shift it away from therestriction position. As a result, as shown in FIG. 53, the magneticforce that the rotor magnet receives varies in accordance with theperiodic pattern of the exciting position numbers.

FIG. 54 is a drawing for explaining the movement of the rotor 150 c ofthe imaging apparatus according to the present embodiment. In FIG. 54,the vertical axis shows a time sequence, which is describedcorresponding to the exciting position numbers. The horizontal axis inFIG. 54 shows the position closer to the restriction end. Regarding thevertical axis, the exciting position numbers show the state of drivingtoward the restriction end.

FIG. 55 is an operation flowchart of the origin reset process of theimaging apparatus according to the present embodiment. This shows theflow that is described as a program in the system control unit 100 ofFIG. 47. When a power supply button is pushed and an instruction ofturning the power on is issued from the operation button 101 to thesystem control unit 100, the process starts with the origin resetprocess start.

The following describes the origin reset process in detail. Inaccordance with an instruction from the calculation unit 201, the I/Funit 205 in the control circuit 200 of FIG. 47 is connected so as toallow a signal to be transmitted to the focus driver 400 and the irisdriver 500, and is connected so as to allow a focusing instructionsignal and an iris adjustment instruction signal to be received from theoutside.

Herein, the focusing instruction signal is an image signal, for example,that is output from an imaging sensor 5 and undergoes a predeterminedimaging process, which contains information for specifying a change inthe focused object distance of an imaging optical system.

The iris adjustment instruction signal is a signal, for example, thatdetects an exposure state based on brightness information output fromthe imaging sensor 5. This signal gives an instruction of narrowing thestop 160 in the case of bright, and gives an instruction of opening thestop 160 in the case of dark.

The counting unit 202 counts driving pulses in accordance with aninstruction from the calculation unit 201. The driving pulses aregenerated by the focus driver 400 and the iris driver 500 in accordancewith the instruction by the calculation unit 201, which are for drivingthe focus motor 150 and the iris motor 160 a. In the case where adriving pulse is generated so that the rotation driving is in thedirection away from the restriction end with reference to the origin,the counting unit 202 decreases the counter, whereas in the case where adriving pulse is generated so that the rotation driving is in thedirection closer to the restriction end, the counting unit 202 increasesthe counter.

The origin storage unit 203 stores the exciting position numbercorresponding to the origin that is detected beforehand, for example, atthe time of shipment. The offset storage unit 204 stores the excitingposition numbers corresponding to the predetermined waiting states ofthe imaging apparatus, such as a wide-angle end focal distance state anda finite object distance focusing state.

In the above-stated configuration, the specific operation of the controlblock will be described below, where the driving of the focus motor 150is exemplified. Firstly, at the time of shipment of the imagingapparatuses, each imaging apparatus is detected concerning the excitingposition number corresponding to the restriction end contacting with therestriction unit, and exciting position numbers at which the rotormagnet receives a magnetic force so as to let it move away from therestriction end with reference to the restriction end are stored in theorigin storage unit 203. More specifically, in the case where theexciting position corresponding to the restriction end is the excitingposition number of 7, any one of the exciting position numbers 4 to 6,which are in the direction away from the restriction end, is storedtherein.

In this state, when electric power is supplied to the imaging apparatus,the process starts with the origin reset process start of the flowchartin FIG. 55. The focus motor 150 is shifted by one step in the directionof the restriction position as shown in Step 501, and the excitingposition number is shifted from 0 to 1 as shown in FIG. 54. Morespecifically, the system control unit 100 gives an instruction to thecalculation unit 201 via the I/F unit 205 so that the focus motor 150 isrotated by one step in the direction of the restriction end. Thecalculation unit 201 counts up the exciting position counter 201 from 0to 1, and reads out the counter value.

The calculation unit 201 sends an instruction to the focus driver 400via the I/F unit so that the current pattern of the exciting positionnumber indicated by this counter value is output to the A-phase coil andthe B-phase coil of the focus motor 150 and the focus motor 150 isdriven by one step in the direction of the restriction end.

Next, in Step 502 of FIG. 55, a judgment is made as to whether movementis N steps or more and it reaches a reference exciting position or not.Herein, N steps show the range of the rotation of the focus motor 150,which is represented with the step number. For instance, this isrepresented with the step number from the start-edge to the end-edge(restriction end).

The reference exciting position is an exciting position that is read outfrom the origin storage unit 203. In the case where the excitingposition corresponding to the restriction end is the exciting positionnumber of 7, any one of the exciting position numbers 4 to 6, which arein the direction away from the restriction end, is stored therein. It isassumed herein that the exciting position number of 5 is stored as thereference exciting position.

Assuming that the focus motor 150 starts to rotate from the start-edgewhen electric power is supplied, unless it reaches the restriction end,the movement is not N steps or more. Therefore, the process returns toStep 501. After that, Step 501 and Step 502 are repeated, so that thefocus motor 150 reaches the restriction end when the exciting positionnumber is 7 (restriction start).

When the exciting position number is 7 in this way, the condition inStep 502 of the movement being N steps or more is satisfied. However,since the reference exciting position is the exciting position number 5,the process further returns to Step 501, where the focus motor 150 isrotated in the direction of the restriction end so as to advance theexciting position number as in 0, 1, 2, 3 and 4. Between the excitingposition number 7, where the focus motor 150 reaches the restrictionend, and the exciting position numbers of 0 to 2, the focus motor 150 ispushed against the restriction end. When the exciting position number is3, the focus motor 150 is kept at the restriction end or is rotated tothe position kept by the excitation. When the exciting position numberis 4, the focus motor 150 is rotated to the position kept by theexcitation as shown in FIG. 54.

Next, in Step 501, when the focus motor 150 is shifted by one step inthe direction of the restriction position and when the exciting positionnumber is 5, the conditions of the movement being N steps or more andthe arrival at the reference exciting position (in this case, theexciting position number 5) are satisfied in Step 502, then the processgoes to Step 503. In Step 503, the absolute position counter 211 isreset. At this time, the absolute position number becomes 0, and theabsolute position of the focus motor 150 is determined, so as tocomplete the origin reset process. With the above-stated process, theorigin of the focus motor 150 is determined.

Following this, the calculating unit 201 reads out the pulse numbercorresponding to the offset movement amount stored in the offset storageunit 204. Herein, the offset movement amount means a movement amount toa specific position that is a predetermined distance away from theorigin.

The specific position that is a predetermined distance away from theorigin may be, in the case of the focus motor 150 for example, arotation position of the focus motor 150 corresponding to the focus soend of the imaging apparatus and a pan-focus region, typically. In thiscase, the offset movement amount specifically is a movement amountspecified with reference to the origin using M pieces of excitingpatterns (M is a positive integer of 1 or more).

In addition, the offset movement amount can be configured variably bysetting the specific position that is a predetermined distance away fromthe origin appropriately using a middle focal position, a positioncorresponding to the telephoto end, focus, iris, zoom positions when thepower is turned off, and the like. In this way, by setting the offsetmovement amount, the time required to make the imaging apparatus readyfor the operation after turning the power on can be shortened.

In this way, according to the present embodiment, simply by adding thecontacting member and the restriction member that restrict the movementof the focus lens, the origin can be detected without using a sensor inthe configuration. In the absence of a sensor, by storing the excitingposition number corresponding to the restriction end beforehand, theorigin may be detected when the pulse is at a position corresponding tothe exciting position number.

However, in the case where the exciting position number corresponding tothe origin is an arbitrary number, the origin cannot be detectedaccurately depending on the selected exciting position number. Morespecifically, in the example of the present embodiment, in the casewhere the position corresponding to the restriction end is at a positioncorresponding to the exciting position numbers of 3 and 7, the positionof the rotor is instable as stated above, and therefore this position isnot suitable for the origin.

Further, at the positions corresponding to the exciting position numbersof 0 to 2, the rotor magnet receives a magnetic force so as to push therestriction position. Thus, since an error may occur when counting themovement amount from the origin, these positions are not suitable forthe origin. For instance, in the case where the origin is set at aposition corresponding to the exciting position number of 2, when thecontacting member 60 contacts with the restriction member 70 as shown inFIG. 52(c), the contacting member 60 pushes the restriction member 70 asdescribed above.

This pushing state does not change even at the position with theexciting position number of 1 in FIG. 52(b). In this case, since theexciting position number changes from 2 to 1, it is judged that thefocus lens is shifted by the amount corresponding to one excitingposition number. However, the focus lens actually is kept at the sameposition, and therefore the movement amount from the origin cannot beunderstood accurately.

Thus, according to the present embodiment, the origin is set at aposition corresponding to the exciting position numbers of 4 to 6. Asshown in FIG. 54, when the exciting position number is advanced from theupper side to the lower side of the vertical axis, after reaching therestriction position, all of the positions corresponding to the excitingposition numbers of 4 to 6 are away from the restriction end.

This is because, as described referring to FIGS. 52(e), (f) and (g), atthe positions corresponding to the exciting position numbers of 4 to 6the magnetic force acts on so that the rotor magnet moves away from therestriction position. Therefore, as the exciting position number isdecreased one by one from this position, the focus lens securely movescorresponding to the exciting position number as illustrated in thelower portion from the origin reset position in FIG. 54.

Thus, according to the present invention, the origin is set at aposition corresponding to the exciting position numbers of 4 to 6, andthe movement from the origin is detected using a step corresponding tothe exciting position number, whereby the rotor can be controlled foralignment accurately without using a sensor or the like.

Incidentally, the above-stated embodiment describes the example wherethe one-two phase excitation type stepping motor is driven in 8excitation patterns with the exciting position numbers of 0 to 7.However, this is not a limiting example, and excitation patterns withina range of 4 to 16 patterns are possible using a different excitationtype stepping motor.

Further, although the example with the exciting position numbers of 0 to7 is described above, the exciting position numbers simply are set forthe sake of convenience, and they may be set differently. For instance,the exciting position numbers may be set at 1 to 8, and in this case,the origin should not be selected from the exciting position numbers of4 to 6 as in the above example, but should be selected from the excitingposition numbers of 5 to 7.

Therefore, many patterns of the representation for the origin can beconsidered. However, this may be represented as follows. In the case ofa stepping motor having n+1 pieces of exciting position patterns from 0to n (herein, n+1 is an even number of 4 or more), assuming that theexciting position number starts from the state where the contactingmember 60 is separated from the restriction member 70 and the excitingposition number is n in the state where the contacting member 60contacts with the restriction member 70 for the first time, then theselection range of the origin will be from (n+1)/2 to n−1.

Embodiment 15

FIG. 56 includes a block diagram of a motor unit and an iris driver ofan imaging apparatus according to Embodiment 15 and a schematic diagramof a stop. FIG. 57 schematically shows the stop in the configuration ofFIG. 56 closer to the restriction end. FIG. 56 and 57 correspond to theiris driver 500 and the stop 160 of FIG. 47, which show the stop 160 indetail.

The imaging apparatus according to the present embodiment uses theoperation principal of the origin reset of the above-stated focus lens.While the member to be driven in the above-stated embodiment is theframe integral with the focus lens, the member to be driven in thepresent embodiment is a rotation member 160 e.

An iris motor 160 a is a stepping motor like the above-stated focusmotor 150, and therefore the detailed explanations of the iris motor 160a is omitted. As shown in FIGS. 56 and 57, the stop 160 is provided witha plurality of light-amount adjustment blades 160 d. The respectivelight-amount adjustment blades 160 d have similar configurations andsimilar functions. Thus, for convenience in explaining, one of thelight-amount adjustment blades 160 d is shown with a solid line, and theoperation of the light-amount adjustment blades 106 d will be describedusing this.

In accordance with a current pattern output from the iris driver 500,the iris motor 160 a rotates to the right as shown in the drawing. Alongwith this, a rotation gear 160 b rotates to the right, and the rotationforce is transmitted to an arc-shaped gear 160 c, which makes therotation member 160 e rotate to the left. During this movement, thepoint of application 162 of the light-amount adjustment blades 160 dmoves along a guide groove 160 f provided in the rotation member 160 ewith a support point 161 as center, so that as shown in FIG. 57, thelight-amount adjustment blades 160 d are driven in the direction ofopening the stop.

Herein, 160 g denotes a restriction member that restricts the stop atits narrowest position, and 160 h denotes a restriction member thatrestricts the stop at an open position. The restriction member 160 hcorresponds to the restriction member 70 of FIG. 47 and the arc-shapedgear 160 c corresponds to the contacting member 60 of FIG. 1. Althoughthe origin of the above-stated focus lens is reset by bringing therestricting member 70 into contact with the contacting member 60, theorigin of the stop in the present embodiment is reset by bringing thearc-shaped gear 160 c into contact with the restriction member 160 h.According to the present embodiment, although an object to be controlledis different from the above-stated embodiment, the basic operation ofthe origin reset is similar to the above-stated embodiment.

As stated above, according to the imaging apparatuses of Embodiments 14and 15, since the exciting position where the rotor receives a magneticforce so as to let it move away from the restriction end of performingthe physical restriction is set as the origin, the origin can bedetermined accurately without the need of alignment using a photosensoror the like.

Herein, in the imaging apparatuses according to Embodiments 14 and 15,at the time of shipment of imaging apparatuses, each imaging apparatusis detected beforehand concerning the exciting position numbercorresponding to the restriction end contacting with the restrictionunit, and an exciting position number set based on this excitingposition number is stored as the origin in the origin storage unit.Instead, an exciting position number corresponding to the origin can beestimated from a range specified from the accuracy of components andassembly accuracy.

More specifically, in the above imaging apparatuses described inEmbodiments 14 and 15, the exciting position number corresponding to therestriction end may be designed within a range of the exciting positionnumbers of 4±1 based on the accuracy of components and alignmentaccuracy, and the position corresponding to the actual origin may be setat a position always returning by the amount corresponding to 3 patternsfrom the exciting position number of the restriction end. With thissetting, the exciting position number corresponding to the origin alwayscan be within the range of the exciting position numbers of 4 to 6, thusomitting an inspection concerning the origin at the time of shipment.

Further, Embodiments 14 and 15 are not limiting examples, and variousmodifications are possible. Although Embodiments 14 and 15 show theexample where the barrel is provided with two stepping motors of thefocus motor and the iris motor, they are not limiting examples. Even inthe case where the imaging apparatus is provided with a zoom motorhaving a zooming function, the present invention is applicable in asimilar manner.

Further, in the case of so-called pan-focus in which focusing is set ata fixed finite image-capturing distance, the motor may be a zoom motoronly. In the case where the imaging apparatus includes a unifocal lenssystem that does not have a zooming function and focusing only isperformed, the motor may be a focus motor only.

As a motor to which the present invention is applicable, an imagefluctuation correction motor that shifts a lens group in the directionperpendicular to the optical axis is available as well. Further, in thecase of a stop motor, a half-stop diameter, which is used frequently,can be considered as the predetermined position for setting an offsetmovement amount. In the case of the image fluctuation correction motor,a position where the optical axis of a lens groups that is in the normaloperation state and the optical axis of the overall system agree witheach other can be considered as such a position.

Further, depending on the movement mode of the imaging optical systemduring zooming, the zoom motor may drive one lens group or three lensgroups. Similarly, depending on the movement mode of the lens duringfocusing, the focus motor may drive one lens group or three lens groups.

Further, a conversion mechanism and a movement mechanism of a barrel towhich the present invention is applicable may include the configurationincluding a rotating cam cylinder and a rotating lens frame coupled witha cam, the configuration including a rotating cylinder and a rotatinglens frame connected with a rotating frame via screws and the like.

Further, although in the stepping motors of Embodiments 14 and 15, astator includes a stator coil and a rotor includes a rotor magnet, theyare not limiting examples. As the stepping motor, a stator may include astator magnet and a rotor may include a rotor coil, and current may besupplied on the rotor side.

With such a configuration of the stepping motor, the moment of inertiaof the rotor can be made smaller and the property of controllingrotation during alignment or the like can be improved. However, ascompared with the configurations of Embodiments 14 and 15, theconfiguration for connecting a driving current to the rotor coil becomesmore complicated. Therefore, the configuration of the stepping motor maybe selected from these depending on desired properties.

Further, at the time of turning power off, following the movement of themotor to the origin, the power may be turned off. Thereby, when power isturned on the next time, an origin reset process is performed by drivingin the direction of the restriction end by one exciting cycle (e.g.,from the exciting position number 5 to the next exciting position number5), so that the starting-time before image-capturing can be shortened atthe time of turning power on. This is effective for an iris motor thatdoes not rotate easily by the application of an external force to theimaging apparatus when electric power is not supplied or for a steppingmotor for driving a light-weight lens. Especially preferably, followingthe movement to the exciting position where self-holding specific to astepping motor is capable, the power is turned off.

INDUSTRIAL APPLICABILITY

The present invention is particularly effective for a digital stillcamera, a digital video camera or the like, which have been demanded tohave a smaller size and higher performance.

1. A lens driving apparatus, comprising: an imaging lens including afocus adjustment lens that forms an image of a subject; an imagingdevice that images light of the subject by way of the imaging lens; alens position controller including a driver that shifts the imaging lensin a direction of an optical axis with respect to a lens barrel, thelens position controller outputting a periodic driving signal andcontrolling a position of the imaging lens using the driver; a positiondetection sensor whose output value varies with a position of theimaging lens; a lens position calculator that determines a phase of thedriving signal as a reference position of the imaging lens when theoutput value of the position detection sensor reaches a threshold value;and a reference position storage that stores the reference position,wherein the lens position calculator determines a position obtained byperforming addition or subtraction on the reference position read outfrom the reference position storage as a judgment position, detects anoutput value of the position detection sensor at a timing insynchronization with the driving signal that drives the driver and atthe judgment position, and judges whether the output value of theposition detection sensor at the judgment position reaches the thresholdvalue or not, so as to determine the reference position again.
 2. Thelens driving apparatus according to claim 1, wherein the driving signalthat drives the driver for determining the reference position is asubstantially sine wave signal.
 3. The lens driving apparatus accordingto claim 1, wherein assuming that a time of one cycle of the drivingsignal that drives the driver for determining the reference position isT, a driving signal that drives the driver for determining the referenceposition again is a M/N periodic driving signal whose one cycle is(M/N)·T, where N=2n (n is an integer of 2 or more) and M is an integersatisfying 2n>M>2.
 4. The lens driving apparatus according to claim 1,wherein the judgment position is located at a position ½ cycle of thedriving signal away from the reference position read out from thereference position storage.
 5. The lens driving apparatus according toclaim 3, wherein the judgment position is located at a position ½ cycleof the M/N periodic driving signal away from the reference position readout from the reference position storage.
 6. The lens driving apparatusaccording to claim 1, wherein the lens position calculator designatesthe judgment position as a stopping position, and the lens positioncontroller shifts the imaging lens to the stopping position beforeturning a power supply of the lens driving apparatus off.
 7. The lensdriving apparatus according to claim 1, wherein the lens positioncalculator determines as a stopping position a position obtained byperforming addition or subtraction on the reference position, the lenscontroller shifts the imaging lens to the stopping position beforeturning a power supply of the lens driving apparatus off, and thestopping position is a position ½ cycle of the driving signal away fromthe reference position.
 8. The lens driving apparatus according to claim3, wherein the lens position calculator determines as a stoppingposition a position obtained by performing addition or subtraction onthe reference position, the lens controller shifts the imaging lens tothe stopping position before turning a power supply of the lens drivingapparatus off, and the stopping position is a position ½ cycle of theM/N periodic driving signal away from the reference position.
 9. Thelens driving apparatus according to claim 1, further comprising anangular sensor that detects an inclination angle of the lens barrel,wherein the lens position calculator determines, based on inclinationangle information of the lens barrel output from the angular sensor, acorrection distance corresponding to a displacement from a referenceangle, and the lens position calculator designates a position obtainedby performing addition or subtraction of the correction distance withrespect to the judgment position as a new judgment position, anddesignates the new judgment position as the position where the outputvalue of the position detection sensor is detected for the judgment. 10.The lens driving apparatus according to claim 1, further comprising anangular sensor that detects an inclination angle of the lens barrel,wherein the lens position controller controls a position of the imaginglens based on correction position information that is based oninformation of the reference position and inclination angle informationof the lens barrel output from the angular sensor.
 11. The lens drivingapparatus according to claim 1, wherein the lens position calculatordetermines as an upper end position of the imaging lens a phase of thedriving signal when the output value of the position detection sensorreaches a threshold value in a state of the lens barrel facing upward,determines as a lower end position of the imaging lens a phase of thedriving signal when the output value of the position detection sensorreaches a threshold value in a state of the lens barrel facing downward,and calculates the reference position based on the upper end positionand the lower end position.
 12. The lens driving apparatus according toclaim 10, wherein the lens position calculator calculates anintermediate position between the upper end position and the lower endposition as the reference position.
 13. The lens driving apparatusaccording to claim 1, wherein the lens position calculator determines asan upper or a lower end position of the imaging lens a phase of thedriving signal when the output value of the position detection sensorreaches a threshold value in a state of the lens barrel facing upward ordownward, and calculates the reference position by performing additionor subtraction of a predetermined distance with respect to the upper orthe lower end position.
 14. The lens driving apparatus according toclaim 1, further comprising a temperature sensor that detects atemperature of the lens barrel, wherein the lens position calculatordetermines, based on temperature information of the lens barrel outputfrom the temperature sensor, a correction distance corresponding to adisplacement from a reference temperature, and the lens positioncalculator designates a position obtained by performing addition orsubtraction of the correction distance with respect to the judgmentposition as a new judgment position, and designates the new judgmentposition as the position where the output value of the positiondetection sensor is detected for the judgment.
 15. The lens drivingapparatus according to claim 1, further comprising a temperature sensorthat detects a temperature of the lens barrel, wherein the lens positioncontroller controls a position of the imaging lens based on correctionposition information that is based on information of the referenceposition and temperature information of the lens barrel output from thetemperature sensor.
 16. The lens driving apparatus according to claim 1,further comprising an angular sensor that detects an inclination angleof the lens barrel and a temperature sensor that detects a temperatureof the lens barrel, wherein the lens position calculator determines,based on inclination angle information of the lens barrel output fromthe angular sensor, an angle correction distance corresponding to adisplacement from a reference angle, and determines, based ontemperature information of the lens barrel output from the temperaturesensor, a temperature correction distance corresponding to adisplacement from a reference temperature, and the lens positioncalculator designates a position obtained by performing addition orsubtraction of a total distance of the angle correction distance and thetemperature correction distance with respect to the judgment position asa new judgment position, and designates the new judgment position as theposition where the output value of the position detection sensor isdetected for the judgment.
 17. A lens driving apparatus, comprising: animaging lens including a focus adjustment lens that forms an image of asubject; an imaging device that images light of the subject by way ofthe imaging lens; a lens position controller including a driver thatshifts the imaging lens in a direction of an optical axis with respectto a lens barrel, the lens position controller outputting a periodicdriving signal and controlling a position of the imaging lens using thedriver; a position detection sensor whose output value varies with aposition of the imaging lens; a lens position calculator that determinesa phase of the driving signal as a reference position of the imaginglens when the output value of the position detection sensor reaches afirst threshold value; and a reference position storage that stores thereference position, wherein the lens position calculator designates as ajudgment position a position having a same phase as a phase of thereference position read out from the reference position storage, detectsan output value of the position detection sensor at a timing insynchronization with the driving signal that drives the driver and atthe judgment position, and judges whether the output value of theposition detection sensor at the judgment position reaches a secondthreshold value different from the first threshold value or not, so asto determine the reference position again.
 18. The lens drivingapparatus according to claim 17, wherein assuming that a time of onecycle of the driving signal that drives the driver for determining thereference position is T, a driving signal that drives the driver fordetermining the reference position again is a 1/N periodic drivingsignal whose one cycle is T/N (N is an integer of 2 or more).
 19. Thelens driving apparatus according to claim 17, wherein the secondthreshold value is a value within a range of an output value of theposition detection sensor between the reference position and a positionone cycle of the driving signal away from the reference position. 20.The lens driving apparatus according to claim 17, wherein the secondthreshold value is an output value of the position detection sensor at aposition ½ cycle of the driving signal away from the reference position.21. The lens driving apparatus according to claim 17, wherein the lensposition calculator designates the judgment position as a stoppingposition, and the lens position controller shifts the imaging lens tothe stopping position before turning a power supply of the lens drivingapparatus of
 22. The lens driving apparatus according to claim 17,wherein the lens position calculator designates as a stopping position ajudgment position that is an immediately preceding of a judgmentposition corresponding to the reference position determined again, andthe lens position controller shifts the imaging lens to the stoppingposition before turning a power supply of the lens driving apparatusoff.
 23. The lens driving apparatus according to claim 17, furthercomprising an angular sensor that detects an inclination angle of thelens barrel, wherein the lens position calculator determines, based oninclination angle information of the lens barrel output from the angularsensor, a correction distance corresponding to a displacement from areference angle, and the lens position calculator designates a positionobtained by performing addition or subtraction of the correctiondistance with respect to the judgment position as a new judgmentposition, and designates the new judgment position as the position wherethe output value of the position detection sensor is detected for thejudgment.
 24. The lens driving apparatus according to claim 17, furthercomprising an angular sensor that detects an inclination angle of thelens barrel, wherein the lens position controller controls a position ofthe imaging lens based on correction position information that is basedon information of the reference position and inclination angleinformation of the lens barrel output from the angular sensor.
 25. Thelens driving apparatus according to claim 17, wherein the lens positioncalculator determines as an upper end position of the imaging lens aphase of the driving signal when the output value of the positiondetection sensor reaches the first threshold value in a state of thelens barrel facing upward, determines as a lower end position of theimaging lens a phase of the driving signal when the output value of theposition detection sensor reaches a threshold value in a state of thelens barrel facing downward, and calculates the reference position basedon the upper end position and the lower end position.
 26. The lensdriving apparatus according to claim 25, wherein the lens positioncalculator calculates an intermediate position between the upper endposition and the lower end position as the reference position.
 27. Thelens driving apparatus according to claim 17, wherein the lens positioncalculator determines as an upper or a lower end position of the imaginglens a phase of the driving signal when the output value of the positiondetection sensor reaches the first threshold value in a state of thelens barrel facing upward or downward, and calculates the referenceposition by performing addition or subtraction of a predetermineddistance with respect to the upper or the lower end position.
 28. Thelens driving apparatus according to claim 17, further comprising atemperature sensor that detects a temperature of the lens barrel,wherein the lens position calculator determines, based on temperatureinformation of the lens barrel output from the temperature sensor, acorrection distance corresponding to a displacement from a referencetemperature, and the lens position calculator designates a positionobtained by performing addition or subtraction of the correctiondistance with respect to the judgment position as a new judgmentposition, and designates the new judgment position as the position wherethe output value of the position detection sensor is detected for thejudgment.
 29. The lens driving apparatus according to claim 17, furthercomprising a temperature sensor that detects a temperature of the lensbarrel, wherein the lens position controller controls a position of theimaging lens based on correction position information that is based oninformation of the reference position and temperature information of thelens barrel output from the temperature sensor.
 30. The lens drivingapparatus according to claim 17, further comprising an angular sensorthat detects an inclination angle of the lens barrel and a temperaturesensor that detects a temperature of the lens barrel, wherein the lensposition calculator determines, based on inclination angle informationof the lens barrel output from the angular sensor, an angle correctiondistance corresponding to a displacement from a reference angle, anddetermines, based on temperature information of the lens barrel outputfrom the temperature sensor, a temperature correction distancecorresponding to a displacement from a reference temperature, and thelens position calculator designates a position obtained by performingaddition or subtraction of a total distance of the angle correctiondistance and the temperature correction distance with respect to thejudgment position as a new judgment position, and designates the newjudgment position as the position where the output value of the positiondetection sensor is detected for the judgment.
 31. An imaging apparatus,in which a lens barrel and a camera main body are detachable, whereinthe lens barrel comprises: an imaging lens group that includes a focuslens and forms an image of a subject; a motor driver that includes amotor that shifts the focus lens in a direction of an optical axis; astorage in which an information table containing control information ofthe focus lens is stored; and a first data transmitter/receptor thattransmits information output from the storage to the camera main body,the camera main body comprises: an imaging device that images light ofthe subject by way of the imaging lens group; a second datatransmitter/receptor that receives information transmitted from thefirst data transmitter/receptor; and a motor controller that controlsthe motor in accordance with received information output from the seconddata transmitter/receptor, wherein the focus lens is controlled inaccordance with information that the motor controller transmits to thefirst data transmitter/receptor via the second datatransmitter/receptor.
 32. The imaging apparatus according to claim 31,wherein the motor driver outputs a periodic driving signal in accordancewith received information output from the motor controller, and themotor shifts the focus lens in the direction of the optical axis inaccordance with the output driving signal, the lens barrel furthercomprises a position detection sensor whose output value varies with aposition of the focus lens, and the motor controller determines as areference position of the focus lens a phase of the driving signal whenan output value of the position detection sensor reaches a thresholdvalue, and transfers information of the reference position via thesecond and the first data transmitter/receptor so as to allow theinformation of the reference position to be stored as information in theinformation table of the storage.
 33. The imaging apparatus according toclaim 32, wherein the motor controller determines as a judgment positiona position obtained by performing addition or subtraction with respectto the reference position read out from the storage via the first andthe second data transmitter/receptor, detects an output value of theposition detection sensor via the first and the second datatransmitter/receptor at a timing in synchronization with the drivingsignal that drives the motor driver and at the judgment position, andjudges whether the output value of the position detection sensor at thejudgment position reaches the threshold value or not, so as to determinethe reference position again.
 34. The imaging apparatus according toclaim 33, wherein the judgment position is located at a position ½ cycleof the driving signal away from the reference position read out from thestorage.
 35. The imaging apparatus according to claim 31, wherein theinformation table comprises at least one of information on the number ofmagnetic poles of the motor, information on a rotation resolution of themotor, information on a driving voltage of the motor and information ona maximum driving rate of the motor.
 36. The imaging apparatus accordingto claim 31, further comprising a temperature sensor, wherein theinformation table comprises correction information by a temperature on aposition of the focus lens, and the motor controller corrects theposition of the focus lens in accordance with a temperature change basedon temperature information of the temperature sensor and the correctioninformation.
 37. The imaging apparatus according to claim 31, furthercomprising an angular sensor, wherein the information table comprisescorrection information by an attitude angle on a position of the focuslens, and the motor controller corrects the position of the focus lensin accordance with an angle change based on angle information of theangular sensor and the correction information.
 38. The imaging apparatusaccording to claim 31, wherein the information table comprisesinformation on operation cycle of the motor, and the information on theoperation cycle is updated in accordance with a movement distance or amovement time of the focus lens from turning on of a power supply of theimaging apparatus to completion of the power supply.
 39. The imagingapparatus according to claim 31, wherein the motor is at least oneselected from the group consisting of a stepping motor, a linear motor,an ultrasound motor, a motor configured with a smooth impact drivingmechanism, an electrostatic motor and a piezoelectric motor.
 40. Theimaging apparatus according to claim 31, wherein parity is added totransmission/reception data between the first transmitter/receptor andthe second transmitter/receptor.
 41. A lens barrel, comprising: animaging lens group that includes a focus lens and forms an image of asubject; a motor driver that includes a motor that shifts the focus lensin a direction of an optical axis; a storage in which an informationtable containing control information of the focus lens is stored; and afirst data transmitter/receptor that transmits information output fromthe storage to a camera main body, wherein the lens barrel is used forthe camera body comprising a motor controller that outputs informationfor controlling the focus lens via a second data transmitter/receptor,and the focus lens is controlled in accordance with information that themotor controller transmits to the first data transmitter/receptor viathe second data transmitter/receptor.
 42. The lens barrel according toclaim 41, further comprising a position detection sensor whose outputvalue varies with a position of the focus lens, wherein the motor isdriven by a periodic driving signal, and when the focus lens is shiftedin the direction of the optical axis in accordance with the drivingsignal, a phase of the driving signal when an output value of theposition detection sensor reaches a threshold value is designated as areference position of the focus lens, and information of the referenceposition is stored as information in the information table of thestorage.
 43. The lens barrel according to claim 41, wherein theinformation table comprises at least one of information on the number ofmagnetic poles of the motor, information on a movement distanceresolution of the motor, information on a driving voltage of the motorand information on a maximum driving rate of the motor.
 44. The lensbarrel according to claim 41, wherein the information table comprisescorrection information by a temperature on a position of the focus lens.45. The lens barrel according to claim 41, wherein the information tablecomprises correction information by an attitude angle on a position ofthe focus lens.
 46. The lens barrel according to claim 41, wherein theinformation table can store information on operation cycle of the motor.47. The lens barrel according to claim 41, wherein the motor is at leastone selected from the group consisting of a stepping motor, a linearmotor, an ultrasound motor, a motor configured with a smooth impactdriving mechanism, an electrostatic motor and a piezoelectric motor. 48.The lens barrel according to claim 41, wherein parity is added totransmission/reception data between the first transmitter/receptor andthe second transmitter/receptor.
 49. A camera main body that is used fora lens barrel, the lens barrel comprising: an imaging lens group thatincludes a focus lens and forms an image of a subject; a motor driverthat includes a motor that shifts the focus lens in a direction of anoptical axis; a storage in which an information table containing controlinformation of the focus lens is stored; and a first datatransmitter/receptor that transmits information output from the storageto the camera main body, wherein the camera main body comprises: animaging device that images light of the subject by way of the imaginglens group; a second data transmitter/receptor that receives informationtransmitted from the first data transmitter/receptor; and a motorcontroller that controls the motor in accordance with receivedinformation output from the second data transmitter/receptor, whereinthe motor controller transmits information for controlling the focuslens to the first data transmitter/receptor via the second datatransmitter/receptor.
 50. An imaging apparatus, comprising: a lensbarrel provided with a first lens unit and a second lens unit, each ofwhich is movable in a direction of an optical axis; a first driver thatshifts the first lens unit in the direction of the optical axis; asecond driver that shifts the second lens unit in the direction of theoptical axis; a controller that outputs a control signal to each of thefirst driver and the second driver; and a position detector that detectsa position of the second lens unit and also detects a position of thefirst lens unit by movement resulting from contact of the first lensunit with the second lens unit.
 51. The imaging apparatus according toclaim 50, wherein the position detector comprises a member to bedetected that moves together with the second lens unit in the directionof the optical axis and a sensor that detects a position of the memberto be detected in the direction of the optical axis.
 52. The imagingapparatus according to claim 50, wherein the position of the first lensunit is detected by bringing the first lens unit into contact with thesecond lens unit by shifting the first lens unit by the first driver,followed by movement of the second lens unit together with the firstlens unit, and by detecting a position of the member to be detected,which moves together with the movement, by means of the positiondetector.
 53. The imaging apparatus according to claim 50, wherein theposition of the second lens unit is detected by shifting the first lensunit together with the second lens unit by the first driver, followed byshifting of the second lens unit by the second driver, and by detectinga position of the member to be detected, which moves together with theshifting of the second lens unit, by means of the position detector. 54.The imaging apparatus according to claim 50, wherein the second lensunit is moveable along a supporting member in the direction of theoptical axis, shifting of the second lens unit by the second driver isperformed by way of a movement restriction unit that is shifted by thesecond driver, shifting of the second lens unit by the first driver isperformed by way of a movement conveying unit that moves to be linkedwith the first lens unit, and the movement restriction unit and themovement conveying unit both are disposed closer to the supportingmember.
 55. The imaging apparatus according to claim 51, wherein theposition detector is a light-transmission type sensor, and the member tobe detected is a photo-interruption member of the light-transmissiontype sensor.
 56. The imaging apparatus according to claim 50, whereinthe first lens unit is a zoom lens unit, and the second lens unit is afocus lens unit.
 57. An imaging apparatus, comprising: a power supply; alens barrel provided with a first lens unit and a second lens unit, eachof which is movable in a direction of an optical axis; a first driverthat shifts the first lens unit in the direction of the optical axis; asecond driver that shifts the second lens unit in the direction of theoptical axis; a controller, when electric power is supplied from thepower supply or when the power supply is shut off, making the firstdriver shift the first lens unit so as to perform predetermined processoperations for supplying the electric power or shutting off the powersupply; and a storage that stores information different between a normalcompletion state and an abnormal completion state, in which in thenormal completion state, the first lens unit and the second lens unitare shifted to storage positions in accordance with a predeterminedprocess operation when the power supply is shut off from a state of thesupplying the electric power, and in the abnormal completion state, theapparatus to which electric power is being supplied is completed in astate different from the normal completion state, wherein when electricpower is supplied after the abnormal completion state, the first lensunit and the second lens unit are returned to the normal completionstate in accordance with the information stored in the storage.
 58. Theimaging apparatus according to claim 57, wherein when electric power issupplied after the abnormal completion state, the first lens unit andthe second lens unit are returned to the normal completion state inaccordance with the information stored in the storage, and the firstlens unit is shifted at least by the first driver so as to perform thepredetermined process operation for supplying the electric power. 59.The imaging apparatus according to claim 57, wherein the storage is anonvolatile memory or a volatile memory driven by a secondary powersupply.
 60. The imaging apparatus according to claim 57, wherein thefirst lens unit is a zoom lens unit, and the second lens unit is a focuslens unit.
 61. A driving apparatus that drives a body to be driven,comprising: a restriction end that restricts movement of the body to bedriven; a stepping motor that drives the body to be driven by rotationof a rotor resulting from a change in exciting position in accordancewith a pattern of an exciting current; a driver that supplies theexciting current to the stepping motor; an origin storage unit thatstores an exciting position corresponding to an origin of the body to bedriven beforehand; a counting unit that counts the exciting positionvarying with the pattern of the exciting current supplied by the driverand an absolute position of the body to be driven corresponding to theexciting position; and a calculation unit that resets the origin,wherein at the exciting position stored in the origin storage unit, therotor receives a magnetic force in such a manner that the body to bedriven is separated from the restriction end after the exciting positionis advanced so that the body to be driven is closer to the restrictionend and when the exciting position is advanced further from a statewhere movement of the body to be driven is restricted by the restrictionend.
 62. The driving apparatus, wherein the calculation unit resets theorigin by reading out the exciting position stored in the origin storageunit, making the driver drive the stepping motor so as to advance theexciting position so that the body to be driven is brought closer to therestriction end, and advance the exciting position from a state wherethe movement of the body to be driven is restricted by the restrictionend to the position corresponding to the read out exciting position, andresetting a value of the absolute position corresponding to thisexciting position.
 63. The driving apparatus according to claim 61,wherein the number of patterns of the exciting current supplied to thestepping motor is n+1 from 0 to n (n+1 is an even number of 4 or more),as the number of the patterns of the exciting current is advanced from 0to n, the body to be driven approaches the restriction end, assumingthat when restriction of movement of the body to be driven is started,the number of the pattern of the exciting current is n, and the excitingpositions have the number of 0 to n corresponding to the respectivenumbers of the patterns of the exciting current, the number of theexciting position corresponding to the origin is within a range from(n+1)/2 to n−1.
 64. The driving apparatus according to claim 61, furthercomprising an offset storage unit that stores an offset movement amountcorresponding to a movement amount from the exciting position stored inthe origin storage unit to a specific position that is a predetermineddistance away from the exiting position stored in the origin storageunit, wherein the calculation unit controls, after resetting the originof the body to be driven, the driver so as to make the body to be drivenmove by the offset movement amount stored in the offset storage unit.65. The driving apparatus according to claim 61, wherein the body to bedriven is a stop that controls a light amount of a subject light.
 66. Alens driving apparatus comprising the driving apparatus according toclaim 61, wherein the body to be driven is a lens supporting frame thatsupports a lens element.
 67. The lens driving apparatus according toclaim 66, wherein the body to be driven is the lens supporting frame anda stop that controls a light amount of a subject light.